I'd be also happy with a solution for this, as for example paypal has ridiculous fees (5-6%) for accepting payment. Of course everyone is choosing paypal over credit card payment (where the fee is only 1-2%) :(
The support recommended this app: https://apps.shopify.com/product-fees
Did anyone try it already?
I just installed this one. Having some difficulty. I actually had the developer support perform the installation. Seemed to be working well but when I tested increasing the quantity of my product with the active fee on the cart page, it completely deleted all products in the cart. It could just be an issue caused by scripting conflicts in the code from other third party apps. But as of now no luck. I'll post back if the developers can get it working properly.