Jason Price was substituted near the end of the game with a possiblen Achilles tendon injury.
Rovers gave away a sloppy goal in the 10th minute as Rocastle pounced on a loose ball in the Rovers penalty area to fire past Sullivan for the only goal of the half.
Rovers looked more liveley in the second half, but conceded two goals inquick succession midway through the half heads dropped, an the game was suddenly beyond all doubt, lost.
A last 92nd minute goal by Taylor consigned Rovers to their heaviest defeat of the season.
Rovers are 9th in the table and are still only a couple of points off of the play-off places, and have played one less game than 6th placed Blackpool. The heat is really on now to latch onto a play-off spot with only 9 games left!