It depends on the studio and on where they are. Some set prices with sales tax already included; some add it at the till because that is the local convention or the legal requirement. Friday Scheduling does not set prices and does not calculate anybody's tax.
The number on a booking page is the number the studio typed. If it is not clear whether tax sits on top of it, ask before you book — the answer is one message, and it avoids a surprise of a few percent at the end.
Services and retail products are sometimes taxed differently in the same place, so a bottle of shampoo added to your bill may carry tax when the service does not.