TOKYO, June 27 (Reuters) - The U.S. dollar held firm against major currencies on Tuesday as tension simmered in Russia and traders looked ahead to U.S. data that may determine the timing of further interest rate hikes.Russian President Vladimir Putin said on Monday he let an aborted mutiny go on as long as it did to avoid bloodshed, a crisis that pushed the dollar to a 15-month high against the rouble.The dollar index fell 0.22% to 102.510, paring a 0.46% gain on Monday.The Russian rouble weakened 0.41% versus the dollar...