Like your plugin! realy easy to use.
I've got one question, i want to use it with a fixed amount. For example the tip is 5 euro. I have filed in the settings and it seems to work. Just one problem, the user can't choose if they want to pay the tip. For example the should be a checkbox is that is checked the amount (5 euro) is added to the cart.
Any idees how i can fix this?