Just do away with tips. It's a terrible and stupid system. If you want to do it as a customer, go ahead, but it should never be considered as part of the employee's compensation. If people aren't willing to do the job for the hourly wage alone with no tips, raise the wage until they are.
In the service industry there's a big difference between doing a job and doing a job /well/. Doing a job well is incentivized by tips.
I've yet to find someone who pays tips for excellent customer service in the big mall stores. I'm sure they exist, but almost no one does it, and this is acceptable. Why?