June 15 (Reuters) - Wall Street"s main indexes were largely unchanged at the open on Tuesday as investors awaited cues from the Federal Reserve this week about whether a recent jump in inflation would prompt a sooner-than-expected tapering in monetary policy. The Dow Jones Industrial Average (.DJI) rose 3.35 points, or 0.01%, at the open to 34,397.10, the S&P 500 (.SPX) opened higher by 0.13 points, or 0.00%, at 4,255.28, while the Nasdaq Composite (.IXIC) dropped 7.51 points, or 0.05%, to 14,166.64 at the opening bell.