Well, first of all, a pot size raise preflop to open would be $3.50, not $2.50.

A minireraise is aces or kings the vast majority of time. I call preflop thinking I'm beat. When he bets $2.75, I'd just call. It sure smells like aces or kings being played by a donk trying to milk it for all it's worth. You're probably beat but for those odds, I'd call. I don't see much point in raising because he does have aces or king more times than not and he's not folding.