Moving up for the second straight day, the rupee today gained a whopping 54 paise to end at 55.54 against the dollar on persistent dollar-selling by exporters. In volatile trade, the rupee resumed lower at 56.25, as against yesterday's close of 56.08 at the Interbank Foreign Exchange (Forex) Market and hovered between 55.53-56.28 per dollar before settling the day at 55.54 per dollar.Yesterday, it recorded a low of 56.52 against the dollar. As a measure to contain dollar demand and help support the rupee, the Reserve bank today hinted at opening a separate dollar window for oil companies