Easier to take with you what you’re prepared to pay for it and then figure it out with the girl.
I find it depends on how into it/ me they are. Have tipped $40, up to $80 (although not at Honey), and been asked for $100 for COF by one of Ken Wong’s other (now retired) girls
have also not paid extra at some places if I’m a regular, if the girl asks for/ offers very high mileage, or if the session was otherwise shitty.