Merchant Fees, Payment Processing Fees

When Setting up Payment processing fees(charges) in the settings, I find that there is only option to enter Discount Fee %. There is no way of entering a fixed amount. This now has ben be done manually now when reconciliation bank account, as my Debit transitions are a fix amount per transition and not a % like Credit Cards. I wish there could be a option to enter a fixed transaction amount and not just a %.