Convenience Fees for VISA Transactions
An interesting thing about accepting VISA.
http://usa.visa.com/download/merchants/rules_for_visa_merchants.pdf

On page 10 of the above linked document.
No Surcharging
Always treat Visa transactions like any other transaction; that is, you may not impose any surcharge on a Visa transaction. You may, however, offer a discount for cash transactions, provided that the offer is clearly disclosed to customers and the cash price is presented as a discount from the standard price charged for all other forms of payment.
Convenience Fees
For merchants who offer an alternate payment channel for customers to pay for goods or services, a convenience fee may be added to the transaction amount. If the merchant chooses to assess a convenience fee to its customers, the merchant must adhere to the following rules:
• The fee is being charged for a bona fide convenience of using an alternative
payment channel outside of the merchant’s normal business practice (see
example below).
• The fee:
– must be disclosed to the customer as a charge for the convenience of using the alternate method to pay
– is applied only to non face-to-face transactions
– must be a flat or fixed amount, regardless of the amount of the payment due
– is applied to all forms of payment products accepted in the alternative payment channel
– is included as part of the total transaction amount
– cannot be added to a recurring transaction
– is assessed by the merchant that provides the goods or services to the cardholder and not a third party
• The customer must be given the opportunity to cancel prior to the completion of the transaction
Example:
The merchant provides utility services to its customers, and the customary way
to pay is by mail or in person at the merchant’s location. For the convenience of
its customers, the merchant also offers a website for payments. In this example,
the merchant may apply a convenience fee to payments made via the website.
For further information on Convenience Fees, please contact your merchant bank.