Tips are not required in everyday life here in China, but if you are staying att a 5 star establishment where the staff is used to western habits, many are somewhat expecting the tips...
My rule of thumb is not to tip except : 1) in international class hotels and restaurants where it just "seems" appropriate; 2) when the service is extraordinary (and yes, it does happen despite the complaining you hear about); and 3) when I know it will promote better service for me and my friends now and in the future (ie. places I go regularly) Do as you see fit and you will be fine. So long as you remember that tipping is NOT required.