Hi:
For a point and click method, using the List Data Task, you will want to use your Customer_Group variable as the "Group By" variable. So in the Variable Role pane, you assign all the other variables to the display role and the Customer_Group variable as the Group By variable for its role and next you can turn on the SUM for Revenue and Balance by specifying them as the variables to sum.
Then, the procedure that is "behind" the List Data Task (Proc PRINT) will automatically give you "subtotals" for each major Group ... Platinum, Gold and Silver -- with a Grand Total of all Groups at the bottom of the report. No counting required. If you have 220 Platinum in one month and 225 Platinum another time, using the Customer_Group variable to provide the "Group By" variable will allow the subtotal to happen at the right place.
For a bit more control over the report, such as being able to change the label on the summary line to the word Subtotal or Grand Total, or to add a blank line between major groups or to use the Customer_Group variable for producing the summary line ... but hiding the Customer_Group variable on the report itself, you would then need to use PROC REPORT.
If you want to lump everybody into 2 categories, instead of 3, you could then have a user-defined format applied to Customer_Group, so that you got the Platinum folks on the report by themselves and the Gold and Silver Folks lumped together. This would give you the Platiinum group and the rest of the folks on your report. The user-defined format approach is nice because it doesn't change the "internal" value of Customer_Group, but you allow you to lump Gold and Silver customers together for purposes of this one report.
cynthia