This feature is currently not available in our API and our modules. It is, however, possible to manually pass on these costs using plug-ins, depending on your platform.
We advise against passing on transaction costs as it could adversely affect your conversion.
Should you choose to pass on the transaction costs anyway, then there is, for instance, a free plug-in available for WooCommerce Payment Fees Lite. For OpenCart there's the free plug-in PayCharge.