In restaurants and for tour guides, a 10% tip is usual, unless service has been deficient. Taxi drivers don't expect to be tipped. Visitors need to be wary of parking attendants. During the day, they should only charge what's on their portable meters when you collect the car but, at night, they will ask for money—usually 1,000 pesos—in advance. This is a racket but, for your car's safety, it's better to comply.