The former Sunderland man, who arrived on a short-term deal at the end of February, helped John Ward's side to a fourth game without defeat.
The visitors stormed into a three-goal lead inside 20 minutes. John-Joe O'Toole - playing his last game of a three-month loan spell from Colchester - hammered high into the roof of the net from close range.
After just six minutes it was two-nil when Tounkara rounded goalkeeper Jonathan Miles and slotted into an empty net.
And Rovers made it 3-0 when Ryan Brunt played in Danny Woodards, who side-footed convincingly past Miles.
Dagenham grabbed a goal back after half an hour when Ben Strevens bundled home Gavin Hoyte's cross, though Medy Elito may have got the final touch as the ball crossed the line.
Tounkara registered his second goal in the 70th minute when he latched on to Woodards' header and smashed the ball home off a post from the edge of the box.
Three minutes later Dagenham substitute Jake Reed tapped home Femi Ilesanmi's cross to make it 4-2 but it proved mere consolation.