By Emily Stephenson WASHINGTON (Reuters) – A U.S. appeals court upheld the Federal Reserves controversial rules for debit card swipe fees on Friday, reversing a lower courts decision to throw them out after merchants argued the charges were too high. Businesses pay the fees to banks when customers use debit cards to purchase goods or services. The fees reimburse banks for costs involved in offering debit cards. At the instruction of Congress, the Fed in 2011 limited the fees to 21 cents per transaction.