BI Publisher 11g Layout Editor - Not Able To Group

When using the 11g web based layout editor I'm not able to collapse and summarize by group in a table.  What I'm trying to do is convert the following detail:

Item              Qty

widgit_1      10

widgit_1      20

widgit_2      10

to:

widgit_1      30

widgit_2      10

This is done easily in Word using <?sum(current-group()/Qty)?>

but in the layout editor I only see Grouping as option, which I can use on the Item column to collapse each unique value.  This doesn't affect the Qty column (I still get all detail rows), so I tried adding a custom formula to the Qty cell, but that didn't give me what I needed.