Barton gets $1.1 million, Rosales $600,000 and Powell $620,000.
Also on Monday, the A's tendered contracts to all the unsigned players on their 40-man roster, including six who remain eligible for arbitration - pitchers Andrew Bailey, Dallas Braden, Joey Devine, Gio Gonzalez and Brandon McCarthy along with outfielder Ryan Sweeney.
Barton made Oakland's opening day roster and started at first base, but struggled and was optioned to Triple-A Sacramento on June 22. He went on the disabled list July 17 because of a right shoulder injury that required season-ending surgery Aug. 12.
Powell played in 36 games for the A's while backing up Kurt Suzuki. Rosales began the 2011 season on the 60-day disabled list with a broken right foot and struggled once he came back June 6. He also spent time in Triple-A.