You would have to use a variable to do this. If you only have one group, you would create two formulas:
{@grptot} to be placed in the group footer:
whileprintingrecords;
numbervar grptot := grptot + sum(field, cond);
{@grptotdisplay} to be placed in the report footer:
whileprintingrecords;
numbervar grptot;
If you are accumulating at a higher group level instead of at the report level, then you would also need a reset formula:
{@resetgrptot} to be placed in group (higher level) header:
whileprintingrecords;
numbervar grptot := 0;
And then you would place {@grptotdisplay} in the group (higher level) footer.
-LB