My dad taught me to tip fairly, he was a salesman most of his life and always left a tip under the plate or saucer.
I tip based on service, I will not tip a rude waiter. A C-note each is a nice tip, if they do a good job and clean up after themselves by all means tip them.
I had a buddy put out bids for three rentals he owned, interior painting only. I Vietnamese guy gave him a bid of $500, my buddy asked $500 each house, the guy said "no $500 all three house." My buddy put five gallons of white in each house for the ceilings, five gallons of landlord blue in one house, five gallons of landlord green in another and five gallons of landlord yellow in the third. The guy called him a less than a week and said "House all done, you come see." My buddy went over and the guy's entire family had worked on the houses, they had taken the paint and mixed it up so different rooms had different color not all one color like my buddy intended, ceilings all white, clean no mess. He gave the guy the top bid a painter had given him, which was $1200 or so, the guy was all "Oh No I say $500, I mean $500." My buddy was beside himself, this guy was such a great worker. He put him onto other jobs he knew of, 1st rate people. I will never understand how people look down their noses at our terrific immigrants that take on all the jobs no native born son will do without expecting an arm and a leg in payment for usually a mediocre job.