BRASILIA, Sept 23 (Reuters) - Brazil’s federal tax revenue in August totaled 146.5 billion reais ($27.6 billion), the revenue service said on Thursday, a record for the month and a 7.25% increase in real terms on the same month last year. Tax revenue in the first eight months of the year totaled 1.2 trillion reais, up 23.5% in real terms over the same period last year, and also a record since the data series began in 1997.