My daughter's clmate's father just opened a bar...?

We see each other and chit chat at birthday parties, and at lunch duty, and even at an after school activity that they both choose to take. My question is, if I decide to go to his bar, should I tip him? I don't want to seem rude if I don't but I don't want to seem condescending if I do tip him. Any standards on how to tip the owner/bartender if you are acquaintances?