A friendly taxi driver or an attentive waiter: In many countries, good service is rewarded with a tip. However, some countries have different rules and customs. Here are six things to look out for when tipping while on holiday. 1. Percentages: In much of Europe, 5-10% of the bill is considered an appropriate tip. You’ll need dig a little deeper into your pockets in the US or Canada, where 15-20% is expected since staff rely more heavily on tips. Just watch out: Sometimes a service charge is already included in the bill. 2. Cash vs card: If you want to make sure the money goes directly to the w…