We love you too, Claudia!
Just FYI, when we tried getting an answer via phone from Profeco on this point, nobody we talked to would even give us one. They said they were sending us a packet of information.
But again, a place that lists prices and notes that 10% sales tax (IVA) will be added, and then does that, is not trying to cheat you (whether it turns out that they are technically in violation of some seldom enforced aspect of consumer protection law for not listing prices with that tax already calculated in or not). For purposes of this particular point and visitors to Playa, the key (as with tips) will be to ask or read the menu carefully or pay attention to relevant signage, in order to know what you're getting into and what will be charged. Like you should do before getting in a taxi, for example.
In other words, like Susie says, be aware.
Steve