How to post final value to header directly in pricing routine

Dear Experts,

I'm having some problem regarding costume pricing routine for SD Module. My requirement is like I have to post the final value form Condition Value

field to header directly. I know it is possible from Amount(KBETR) field, but we have to do it by using Condition Value(KWERT) field. Bcoz if I'm using KBETR some unwanted rounding is happening and final value is coming wrong. In our case we used to have only single Line Item . Please let me know how to do it.

Thanks,

Sombhu