You can pay tips to the staffs of hotel and tourism service industry if you are satisfied with their services although we do not have any custom or habit of tipping. And how much for tips? It depends on you and no one would complain about that matter.
And please be careful when you are about to offer monetary help to monks and nuns you see on the road. They probably may not be real monks and nuns. If you really want to help and/or donate, you should consult with local people and find the right place you’re looking for.