With higher Bitcoin and Ethereum fees, accounting for the cost to send each transaction is increasingly important.
Your admin includes the ability to set a Fixed Fee and a Minimum Tx (transaction), in addition to your standard commission percentage:
When setting a fixed fee, the user is charged a flat amount for the transaction in addition to your commission.
A user begins her transaction by scanning the QR code of her wallet. She is then shown the following screen, indicating your exchange rate which includes your commission percentage, and a separate line indicating that there is a $2 fee for placing the transaction:
If she inserts $100, it would be as if she inserted $98 and your commission is included in the amount of bitcoin which you dispense in exchange for $98. If your commission is 7%, you retain $6.86 worth of Bitcoin on the trade as proceeds, with an additional $2 to subsidize your transaction fee expenses.
A minimum transaction can be used in conjunction with a fixed fee or by itself.
If a user begins his transaction by inserting a bill whose denomination is less than your minimum transaction, it will return the bill and request that the user insert a bill whose denomination is greater than that minimum.
After starting a transaction with a bill larger than your minimum, bills of any denomination can be used thereafter.