Agent Commission in PP

Dear Fnds,

For some Sales orders i Need to give Agent Commission ,This commission is based on the sales

document value.

Here requirement is ,Every Agent ,we r making as Vendor (XK01).

I maintained 1 condition type in PP(AG01-Agent commission).and I'll trigger when ever i requires in sales order

Lets say sales order value is 1000/-

iam giving 10% commission so its becomes 100/- and Order value is showing 1100/-

Sales order value should be 1000/- only.

This 10% should not effect the Order value,just its calculate the Percentage .....100/- and it should update in Vendor account.

Thanks in Advance

Regards

raj.