I offer PayPal as a payment option using the integrated PayPal Express functionality. However, I do not absorb the PayPal fee I am levied by PayPal for accepting payments; I pass the charge on to customers on their invoice as a line item, which I currently add manually.
If the client wishes to pay by bank transfer or cheque, which occasionally happens, I have to modify and reissue the invoice without the fee listed.
It would be useful if InvoicePlane could automatically calculate the PayPal fee based on the total invoice amount and automatically add that to the invoice.
It would also be very convenient if it could automatically remove the fee and update the invoice automatically if the client or myself marks the invoice as paid via another method.