Group Header - put aggregate in correct column

Hello,

Is this still the best way to do this?  I need to display summed values on the Group Header row.  One for each column.   The value needs to align with the column(s) that are being summed. 

But, the number of columns (that need to be summed) is unknown until run time.  In the example it looks like a static number of columns are added (2) to the group header row.  The number of columns can change as the application is run.

Thanks,

Mike Baxa