How to do multiple columns total in gridview footer?

Question

<asp:GridView ID="GridView1" runat="server" AllowPaging="True" AutoGenerateColumns="False" OnRowEditing="GridView1_RowEditing" AutoGenerateDeleteButton="true" OnRowDeleting="GridView1_RowDeleting" OnRowUpdating="GridView1_RowUpdating" OnRowCancelingEdit="GridView1_RowCancelingEdit" OnRowDataBound="GridView1_RowDataBound" Font-Names="KF-Kiran" ShowFooter="True" TabIndex="16" Width="90%" CellPadding="3" BackColor="White" BorderColor="#E7E7FF" BorderStyle="None" BorderWidth="1px" GridLines="Horizontal" DataSourceID="SqlDataSource1">

<%----%><%--DataSourceID="SqlDataSource1"--%>

<Columns>

<%--<asp:TemplateField HeaderText="vaaZ"

SortExpression="Saves">

<ItemTemplate>

<asp:TextBox ID="txtIncrement" runat="server" Width="40px" Text='<%#Eval("Increment") %>'/>

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtIncrement" runat="server" Width="40px" Text='<%#Eval("Increment") %>'/>

</EditItemTemplate>

<%--<FooterTemplate>

<asp:TextBox ID="txtIncrement" runat="server" Width="40px"/>

</FooterTemplate>

</asp:TemplateField>--%>

<%--<asp:TemplateField HeaderText="vaaZ"

SortExpression="Increment2">

<ItemTemplate>

<asp:Label ID="txtIncrement2" runat="server" Width="60px" Font-Bold="true" AutoPostBack="true" Text='<%#Eval("Increment2") %>'/>

</ItemTemplate>

<EditItemTemplate>

<asp:Label ID="txtIncrement2" runat="server" Width="60px" Font-Bold="true" Text='<%#Eval("Increment2") %>'/>

</EditItemTemplate>

<FooterTemplate>

<asp:Label ID="txtIncrement2" runat="server" Width="60px"/>

</FooterTemplate>

</asp:TemplateField>--%>

<asp:TemplateField HeaderText="A.kx`." SortExpression="">

<ItemTemplate>

<b>

<asp:Label ID="lblSrNo" runat="server" ForeColor="#cc0000" Text="<%#Container.DataItemIndex+1 %>" />

</b>

</ItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="kxamaacao naava" SortExpression="Work_Name">

<ItemTemplate>

<asp:Label ID="txtWork_Name" runat="server" Font-Bold="true" Text='<%#Eval("Work_Name") %>' Width="150px" />

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtWork_Name" runat="server" Font-Bold="true" Text='<%#Eval("Work_Name") %>' Width="150px" />

</EditItemTemplate>

<FooterTemplate>

<b style="font-family:Arial">Total Calculation:-</b>

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="ToMxDr" SortExpression="Tender">

<ItemTemplate>

<asp:TextBox ID="txtTender" runat="server" OnTextChanged="txtTender_TextChanged1" min="1" max="150" MaxLength="3" AutoPostBack="true" Font-Bold="true" Text="0" Width="60px" />

<asp:RangeValidator ID="RangeValidator1" Font-Names="arial" runat="server" ErrorMessage="0-150 only" MinimumValue="1" MaximumValue="150" ControlToValidate="txtTender"></asp:RangeValidator>

<asp:Label ID="lblError" runat="server" />

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtTender" runat="server" Font-Bold="true" Width="60px" />

</EditItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="pauiva_ idlaa" SortExpression="Advance">

<ItemTemplate>

<asp:TextBox ID="txtAdvance" runat="server" Font-Bold="true" Text="0" Width="60px" />

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtAdvance" runat="server" Font-Bold="true" Width="60px" />

</EditItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="pa`tyaXa" SortExpression="Real_Val">

<ItemTemplate>

<asp:TextBox ID="txtReal_Val" runat="server" OnTextChanged="txtReal_Val_TextChanged1" AutoPostBack="true" Font-Bold="true" Text="0" Width="60px" />

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtReal_Val" runat="server" Font-Bold="true" Width="60px" />

</EditItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="bacata" SortExpression="Saves">

<ItemTemplate>

<asp:Label ID="txtSaves" runat="server" Font-Bold="true" Text="0.00" Width="60px" />

</ItemTemplate>

<EditItemTemplate>

<asp:Label ID="txtSaves" runat="server" Font-Bold="true" Width="60px" Text='<%#Eval("Saves") %>' />

</EditItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="vaaZ" SortExpression="Increment">

<ItemTemplate>

<asp:Label ID="txtIncrement" runat="server" Font-Bold="true" Width="40px" Text="0.00"/>

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtIncrement" runat="server" Font-Bold="true" Width="40px" Text='<%#Eval("Increment") %>'/>

</EditItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="dxr" SortExpression="Rate">

<ItemTemplate>

<span style="font-family:Arial;font-size:10px">Rs.</span>

<asp:Label ID="txtRate" runat="server" AutoPostBack="true" Font-Bold="true" style="font-family:KF-Kiran;" Text='<%#Eval("Rate") %>' Width="50px" />

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtRate" runat="server" Font-Bold="true" style="font-family:KF-Kiran;" Text='<%#Eval("Rate") %>' Width="50px" />

</EditItemTemplate>

<FooterTemplate>

<span style="font-family:Arial;font-size:15px">Rs.</span>

<asp:Label ID="lblTotalRate" runat="server" Font-Bold="true" Font-Size="X-Large" style="font-family:KF-Kiran" Width="50px" />

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="ToMxDr" SortExpression="Tender2">

<ItemTemplate>

<asp:Label ID="txtTender2" runat="server" AutoPostBack="true" Font-Bold="true" Text="0.00" Width="60px" />

</ItemTemplate>

<EditItemTemplate>

<asp:Label ID="txtTender2" runat="server" Font-Bold="true" onkeyup="CalculateTotals();" Width="60px" />

</EditItemTemplate>

<FooterTemplate>

<asp:TextBox ID="lblTotalTender2" runat="server" OnTextChanged="lblTotalTender2_TextChanged" Text="0.00" Font-Bold="true" Font-Names="KF-Kiran" />

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="pa`tyaXa" SortExpression="Real_Val2">

<ItemTemplate>

<asp:Label ID="txtReal_Val2" runat="server" AutoPostBack="true" Font-Bold="true" Text="0.00" Width="60px" />

</ItemTemplate>

<EditItemTemplate>

<asp:Label ID="txtReal_Val2" runat="server" Font-Bold="true" Text='<%#Eval("Real_Val2") %>' Width="60px" />

</EditItemTemplate>

<FooterTemplate>

<asp:Label ID="lblTotalReal_Val" runat="server" Font-Bold="true" Font-Names="KF-Kiran" />

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="bacata" SortExpression="Saves2">

<ItemTemplate>

<asp:Label ID="txtSaves2" runat="server" AutoPostBack="true" Font-Bold="true" Text="0.00" Width="60px" />

</ItemTemplate>

<EditItemTemplate>

<asp:Label ID="txtSaves2" runat="server" Font-Bold="true" Text='<%#Eval("Saves2") %>' Width="60px" />

</EditItemTemplate>

<FooterTemplate>

<asp:Label ID="lblTotalSaves" runat="server" Font-Bold="true" Font-Names="KF-Kiran" />

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="vaaZ" SortExpression="Increment2">

<ItemTemplate>

<asp:Label ID="txtIncrement2" runat="server" Width="60px" Font-Bold="true" AutoPostBack="true" Text="0.00"/>

</ItemTemplate>

<EditItemTemplate>

<asp:Label ID="txtIncrement2" runat="server" Width="60px" Font-Bold="true" Text='<%#Eval("Increment2") %>'/>

</EditItemTemplate>

<FooterTemplate>

<asp:Label ID="txtIncrement2" runat="server" Width="60px"/>

</FooterTemplate>

<FooterTemplate>

<asp:Label ID="lblTotalIncrement" runat="server" Font-Bold="true" Font-Names="KF-Kiran" />

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderStyle-Font-Names="arial" HeaderText="Action">

<ItemTemplate>

<asp:ImageButton ID="imgEdit" runat="server" CommandName="Edit" Height="20px" ImageUrl="~/Images/edit (9).png" Text="Edit" />

<asp:ImageButton ID="imgDelete" runat="server" CommandName="Delete" Height="20px" ImageUrl="~/Images/close (2).png" Text="Delete" />

</ItemTemplate>

<EditItemTemplate>

<asp:ImageButton ID="imgUpdate" runat="server" CommandName="Update" Height="20px" ImageUrl="~/Images/Update.png" />

<asp:ImageButton ID="imgDelete" runat="server" CommandName="Cancel" Height="20px" ImageUrl="~/Images/Cancel.png" />

</EditItemTemplate>

<HeaderStyle Font-Names="arial" />

</asp:TemplateField>

</Columns>

<AlternatingRowStyle BackColor="#F7F7F7" />

<FooterStyle BackColor="#B5C7DE" ForeColor="#4A3C8C" />

<HeaderStyle BackColor="#4A3C8C" Font-Bold="True" ForeColor="#F7F7F7" />

<PagerStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" HorizontalAlign="Right" />

<RowStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" />

<SelectedRowStyle BackColor="#738A9C" Font-Bold="True" ForeColor="#F7F7F7" />

<SortedAscendingCellStyle BackColor="#F4F4FD" />

<SortedAscendingHeaderStyle BackColor="#5A4C9D" />

<SortedDescendingCellStyle BackColor="#D8D8F0" />

<SortedDescendingHeaderStyle BackColor="#3E3277" />

</asp:GridView>

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:Road_PMCConnectionString %>" SelectCommand="SELECT [Work_Name], [Tender], [Real_Val], [Saves], [Increment], [Rate], [Tender2], [Real_Val2], [Saves2], [Increment2] FROM [tblIncrement_Details]"></asp:SqlDataSource>