Disagree. Tipping overall is not good. It's almost like paying ransom. Raise the prices or ask for a higher percentage. Relying on tips is not the way to go.
Theoretically, I agree with you.
Kach yozma (like they say here) and charge what you want to charge - it is your business. (In IL, I avoid the stores where price is a negotiation because I can't stand the concept.)
However, there's a
hakol lefi hainyan a mile wide here.
For instance, take taxi drivers in EY. They get taxed a crazy amount. (It's a cash business, and they claim that the government assumes that they don't report anywhere near their earnings and therefore overtaxes what they HAVE to say they earned. Might even be true.) Rabbi Berkovits has
paskined that you must use a meter when you take an IL taxi, or at least get a printed receipt, because paying them in cash without a receipt is
lifnei iver deoraysa. (His opinion. I am not taking any flak for it. If you have a problem, argue with him.) The proof is how hard they argue when you insist on a meter (had one guy go down 20 shekel when I asked him for a meter).
Therefore, assuming they are courteous and don't drive like maniacs, I always tip generously. Sometimes I even promise them a tip so that they will use the meter.
I am also consciously aware that my behavior reflects on other frum Jews. This means I err on the side of caution when dealing with a Chiloni and when dealing with Arabs.