In Spreadsheet, using formula like XFGETCELL it would be possible. But not directly from the quickview. Maybe VBA can help, if you use the excel addin.
Or if you import your quickview from a cube view, then the total is inherited from your cube views
The easiest way is to use the hierarchy's parent members, i.e., Revenue + Cost of Revenue = Gross Profit, so Gross Profit would be your total column. If that isn't available, you can use the Member Filter Builder to do some math.