Crystal Report Xi: Calculate the grand total

Question

The field you see in the report is a formula field

 

if isnull({ColorTable1.EmployeeRate})

THEN Round ({ColorTable2.numEmployeeRate}*{ColorTable2.numActualQuantity}, 2)

ELSE Round ({ColorTable1.numEmployeeRate} * {ColorTable1.numActualQuantity}, 2)

 

Now from the formula above I am trying to pull the grand total by group in the reporter footer. I tried running total and the math is not adding up, How do I accomplish this in crystal repports