Preston striker Jon Parkin had the first chance of the game with a 15-yard left-foot shot saved by Doncaster goalkeeper Neil Sullivan after four minutes from a Paul Coutts pass.
A long throw-in came into the Preston box and Jay Emmanuel-Thomas forced a save from Preston goalkeeper Andrew Lonergan.
Keith Treacy had a 20-yard shot saved at the near post after 20 minutes. Emmanuel-Thomas then had a low shot saved, with Youl Mawene heading the rebound away.
James Coppinger's cross found Sharp and his shot was saved after 25 minutes.
Coppinger's cross came to Gareth Roberts and he had a 30-yard shot palmed away by Lonergan for a corner.
Coppinger's outswinging corner came to Roberts on the left, who crossed to James Hayter in the middle who scored into the bottom left corner from 12 yards in the 29th minute.
Left-back Tom Williams hobbled off and was replaced by Preston captain Callum Davidson in the 35th minute.
James Chambers fouled Sean St. Ledger and was booked in the 42nd minute
Treacy crossed the free-kick to man-of-the-match Mawene, who passed the ball back to Neil Mellor in the area and he equalised with three minutes left until half-time.
Mark Wilson was booked for a foul on Mellor after 45 minutes.
Sean St Ledger pushed Chambers in the box and referee Phil Crossley awarded Rovers a penalty ten minutes into the second half. Sharp's hard and true placed spot-kick to Lonergan's right was superbly saved by the home goalkeeper.
Soon after Danny Mayor replaced Treacy, before Parkin flicked to Mellor and his shot was saved by Sullivan.
Matthew James come on for Richard Chaplow in the 65th minute, before Mayor, on the left, played the ball to Parkin who spun and his shot was saved by Sullivan.
Dean Shiels replaced Coppinger in the 77th minute and Rovers made a change soon after as Martin Woods took over from Sharp.
Mayor crossed to James who shot straight at Sullivan two minutes from time as both sides were forced to settle for a point.