Follow along with the Tableau attached packaged workbook to review the steps below.  The workbook can be found at the bottom of the article in the Attachments section.

Step 1 - Create a calculated field

1. Select Analysis > Create calculated field
2. Name the calculated field "New Totals"
3. Enter the following formula and click OK: 

   IF WINDOW_COUNT(ATTR([Category]))=0 THEN SUM([Quantity])
   ELSEIF WINDOW_COUNT(ATTR([Category]))=3 THEN SUM([Profit])
   ELSE SUM([Sales])
   END

Build the view

1. Drag Category and Sub-Category to Rows
2. Drag the new calculated field to Text
3. Click Analysis > Totals > Show Column Grand Totals
4. Click Analysis > Totals > Add All Subtotals

Important: The result of window_count depends on the data and the view, and such results will be effected by filters. We recommend using this workaround after sufficient testing.