The Russian rouble edged slightly higher on Friday, supported by monthly tax payments, with trading thin because of the Good Friday holiday in Western markets. At 0725 GMT, the rouble was 0.1 percent stronger against the dollar at 68.48 and had gained 0.4 percent to 76.51 versus the euro. Brent crude oil, a global benchmark for Russia's main export, was down two cents at $40.45 a barrel, having firmed above $40 per barrel on Thursday evening after data showed a renewed decline in US oil rigs.