Ince Jr was almost in trouble with his father and manager Paul Ince after missing a sitter just minutes earlier.
Thomas was gifted the ball by Doncaster defender Paul Quinn at 1-1 in the 84th minute but rolled his close-range shot wide of the mark with only the goalkeeper to beat.
Paul Ince said: "It was a great chance for him to win the game for us and I wasn't happy at all at the time.
"But he kept his head up and then he scores one from near the halfway line. He knew what he was going to do before the ball came to him.
"His execution was perfect, so I won't be too hard on him on the one he missed."
Blackpool scored first in a scrappy match when Steven Davies tapped home from close range in the 17th minute after Ross Turnbull had twice parried shots from Angel Martinez and Kirk Broadfoot.
Rovers battled back to equalise with a towering header from skipper Paul Jones on the hour mark following a corner from David Cotterill.
But Gary MacKenzie scored a carbon copy to restore Blackpool's lead in the 87th minute from Ince's corner kick.
Ince put the icing on the cake deep into injury time when he fired into the unguarded net after Turnbull had gone up for a Rovers corner and failed to race back into his net in time.
Manager Ince added: "It was a hard game but I thought we were worthy winners in the end and I don't think the final score flatters us at all.
"Once we settled into our stride we played quite well despite missing numerous chances.
"It put them back in the game when they equalised but my boys have got a great camaraderie about them and they never give up.
"We haven't had the best preparation with other issues during the summer but the lads have prepared themselves and I was really pleased for them."
- Sports & Recreation
- Paul Ince
- Ross Turnbull