No, but there may be ways to include fields that report the grand summary totals as part of your sub summary part.
Here's one example:
If you have summary field that computes a sub-total in your sub summary part named sTotalSales, you can define a calculation field, cGrandTotalSales and enter sTotalSales as the sole item as its calculation.
Then you can place sTotalSales in your Sub Summary part for the sub total and can place cGrandTotalSales in the same part to show the grand total.
Thank you! I'm not sure why, but this worked perfectly!
Calculations that refer to summary fields get a value based on the current found set--which is your grand total here. If you do want just the current record's sub total as might be shown in a sub summary part in your calculation, you have to use the get Summary (SummaryField ; Breakfield ) function where the "break" field serves the same purpose as the "sorted by" field in a sub summary part's definition.
Thus, the cGrandTotalsales calculation field is a trick that enables you to show the grand total inside your sub summary part.