By Howard Schneider and Ann Saphir WASHINGTON (Reuters) – The Federal Reserve raised interest rates by three-quarters of a percentage point again on Wednesday and said its battle against inflation will require borrowing costs to rise further, yet signaled it may be nearing an inflection point in what has become the swiftest tightening of U.S. monetary policy in 40 years. The double-sided message left open the possibility the U.S. central bank may raise rates in smaller increments in the future, ending its sequence of three-quarters-of-a-percentage-point hikes as soon as December in favor of mo…