I agree with PPs. It's a terrible idea. The minimum wage is high enough that it simply isn't required. I personally enjoy being able to reward truly exceptional service when I see it by tipping or, more often, purchasing something for the worker (flowers, a drink, etc. depending on their job and circumstance) rather than having to pay extra to everyone, no matter how lackluster their performance, because their employer isn't paying them enough to get by.
And that's enough before I start a huge rant about why it's the stupidest idea since lead make-up. Ugh.