Ok, since this contribution doesn't work well and as it is the same like the old "fixed payment type charge" I have made a change to the original contrib to accept both a fixed value and a percentage from the total. You can find it here : http://www.oscommerce.com/community/contributions,251
It allows to enter either a fixed value or a percentage of the total payment, e.g.
cod:15,cc:%3.5
This example will add $15 to the total amount for COD or 3.5% of the total with Credit Card payment.
For an upgrade just copy the file /includes/modules/order_total/ot_fixed_payment_chg.php over the current one and andjust in the admin section of your shop.
- Roger, Switzerland