In your group header you can place a formula which resets the flag =>
Global booleanvar varIncomplete;
varIncomplete := False;
Then on your detail section you can create a formula that sets the flag value, you will need to play with it but something like =>
WhileReadingRecords;
Global booleanvar varIncomplete;
if yourfieldnamehere = 0 then
varIncomplete := True
Then your suppress formula for your subtotal or incomplete would be something like =>
your subtotal => varIncomplete = True or just varIncomplete
your incomplete => varIncomplete = False or just Not varIncomplete