I'm happy to announce Payment Method Fees - a new module for X-Cart 5:
The module allows you to configure surcharges to cover related processing fees.
Since this is something that can be prohibited by the agreement with your payment provider or by your country laws, the module also allows you to set discounts for payment methods so that you could include processing fees into your product prices and let customers choose those methods that are more cost effective
Feel free to ask in this forum thread should you have any questions about the module. Or use the e-mail address shown on the module page.