def not per drink otherwise you may as well not have AI we normally just give the servers/bar staff once a night if they dont make us wait for long periods.

We tip the waiter/waitress IF we are getting service at the table -usually every two rounds of drinks and a small amount. We never tip the bar staff if we are standing at the bar to get a drink.
Unfortunately, some people think its the norm to tip extravagantly all the time which raises staff expectations -we were talking to a couple on a recent holiday to Mexico in an AI who had taken $800 in cash FOR TIPPING

We usually take plenty of US $1 dollar bills as you tend to get pestered in some places for tips and for services that you don't ask for but get hassled to accept. We try to avoid unnecessary tipping but realise wages are poor and do reward good service.