George Boyd, Aaran McLean and Craig Mackail-Smith all found the net as a weakened Millers team bowed out against some high tempo football.
It was Rotherham however that took an early lead, Marcus Marshall putting them infront with a close range finish inside ten minutes.
Ryan Bennett hit back for the home side, who had started sluggishly, by heading in a left wing corner as he beat Luke Ashworth in the air.
Boyd then caught out 'keeper Andy Warrington at his near post just four minutes later, with a drilled shot left footed into the near bottom corner after Rotherham failed to react to a shortly worked free-kick.
After the break began with one way traffic and McLean netted on the hour to effectively end proceedings before he was stretchered off following a late tackle by Danny Harrison in midfield.
Mackail-Smith sealed the win with five minutes left as he caught the visitors asleep and poked home from close range.
The Millers best efforts of the second half saw a rasping shot from Jason Taylor fly over the crossbar and Adam Le Fondre's curled effort drift wide of the far upright.