As of January 27, 2013 businesses can charge their customers a surcharge on credit card transactions. It's important to note that the fee is charged by the merchant and not by your financial institution.
While the new rule allows this surcharge it also requires the business to:
For more information please visit http://usa.visa.com/personal/using_visa/checkout_fees/index.html
notify customers before the purchase by placing notices at the store entrance and at the point of sale (usually the cashier's counter)
notify online customers on the first page that references credit card brands and
they must disclose the amount of the fee on the receipt