Your "Rounding PCR" could start with a query on the last split (using operation WPALL?LAST ).
For return value Y, add amount of temporary variable to amount of last split and then round off.
For return value *, transfer amount to temporary variable (using operation ADDWT& xxxx) without returning the split to the Input Table.
Alternatively, in a PCR preceeding the "Rounding PCR", use operation ELIMI to eliminate the undesired splits.