It looks like you cannot create formulas for sum totals to add specific columns in Excel 2007. The way to do this is to use Calculated Item, which uses the original source data to calculate the totals again based on the new formula.
Can you add sum totals directly in Excel 2010 instead of putting a column to the right that is not part of the pivot table?
Can you add sum totals directly in Excel 2010 instead of putting a column to the right that is not part of the pivot table?