Grains tumbled Tuesday as a revived dollar sucked more money out of some commodities, but oil bucked the trend by rallying more than 1%. The Reuters-Jefferies CRB index of 19 commodity futures, considered a proxy for the sector, was down most of the session as the dollar rose for a second day. But the index managed a 0.03% gain when it closed at 275.97. Investors sought shelter in the greenback after weak consumer confidence data fed economic