Hi Steve, and others.
We've been asking Softrak for years to have a Misc Charge similar to your % for CC fees. Maybe it will gain traction if someone other that myself requests it.

We would definitely support (again) this request.

Our clients wanted to have this to be considered for a shipping charge that could be assigned by default or even if manually added so that the fee being charged would be a % of the order total.

Ideally, since we have waited this long, someone should be able to make such a type of misc charge with a conditional formula, that could suppress if the order value was over a certain amount, or in your situation, enabled if the Payment Method was defined as say Credit Card.

Thanks,
Brian