Tips are not customary in Spain. Everyone has a salary. If the service is really good, we usually round up the bills—leaving, say, 100 euros for an 85-euro meal. Same in a taxi. If the driver is nice and the fare is 4 euros, you give 5. On the other hand, if you don’t have change or don’t want to tip, there is no rule that says you have to.
BEFORE YOU GO
In Barcelona: at the Picasso Museum buy a ticket online or you’ll wait forever to get in.