National experts say there's really no way to know how many businesses will add the processing fee to their customers bottom line.
Consumer advocates say folks should never 'check out' when settling up--every business adopting a credit card fee has to have a sign by the register.
If you ever waffle about which card to use, experts say additional charges don't apply to American Express or Debit card users. They also say cash remains king.
National experts say websites that impose credit card fees must post something about those fees on their homepages.