General rule for being pot-committed?

[ddagt]

At what point is one pot-committed to a hand when you're fairly sure you are beat at a full-ring game? If you have over half of your stack in a pot, should you typically call an all-in bet or raise?

An example, you have 100BB, raise in late position with high PP to 5BB, get two callers. On draw-heavy flop you bet 15BB, get two callers. On blank turn you bet 45BB, and get check-raised. They could have either a set/2-pair/TPGK, but probably a set. Is a fold still OK?

Or is it best to assign a range or probable hands, and determine the pot odds, even if you have %50-%75 of your stack in the pot already?

Thanks.