I have a scenario where we add surcharges to Card Based Payments. The surcharges vary by the type of card used ie: Eftpos(Debit) or Amex or (Master/Visa).
The challenge is we need to be able to add/remove surcharges at the point of sale ie:a button that we can click to add the surcharge + clicking again removes the surcharge. This is to cater for scenarios where customers change their mind at the till ie: First wanting to pay by Credit Card of choice = surcharge added and later deciding to pay cash instead.
Calculation Types can be used for this. You can have fixed amount for surcharge. Use Calculation Selectors to assign buttons at the Payment Screen.
You may want to create a new Account Type to list these separately under Accounts.