I did it in a SPA... but they didn't ask for it... just when I was paying with my CC, the machine will ask how much you would pay.....
I am just not sure how much to put in thou..... =( or do we even pay? but I did 45 min for $100.80.... $90 will get covered from work... so really... shall i pay an extra $10 as tips? just don't wanna look cheap and ugly when walking out the door