Tattoo tipping ettiquette?

[chasethefeeling]

I'm getting a tattoo in a week (half sleeve! Chapel tattoo! Fuck yeah!) and I was wondering if you lovely melbournites can educate me on tipping ettiquette? At restaraunts I kinda just round up a note and now that I pay for my own haircuts I tip (because Miss Kat at wildilocks is lovely!) but thats about all the experience I have... is it appropriate / common to tip tattoo artists here? (if so, a percentage or standard?)

thanks! I hope it's not too early to wish you all a merry and not too hot Christmas! :)