If you want to really ROUND, use the ROUND function, or cast to decimal - either of the following:CASE WHEN [Possible Attendance] IS NULL OR [Possible Attendance] = 0 THEN NULL ELSE ROUND(100.0 * [Actual Attendance] / [Possible Attendance],0)END AS PercentageAttendanceCASE WHEN [Possible Attendance] IS NULL OR [Possible Attendance] = 0 THEN NULL ELSE CAST(100.0 * [Actual Attendance] / [Possible Attendance], as decimal(18,0))END AS PercentageAttendance