当：decimal sum = 123456.784M;


sum = decimal.Round(sum, 2 , MidpointRounding.AwayFromZero);


sum 的值为：123456.78


当：decimal sum = 123456.785M;


sum = decimal.Round(sum, 2 , MidpointRounding.AwayFromZero);


sum 的值为：123456.79