Protocal for tipping Valet.s (sorry bout the 500th tipping thread)

[ISF]

I have a parking garage in my building which is valet. Its in manhattan if that matters. I pick the car up every day at the same time what type of tip here is standard.
I have had a car in the city for a while, but this if the first time I have used it regularly. When I used it infrequently I always tipped like 5 or so. I see some of the regulars tip, and some dont. Aa well I pay 325 a month to park it if that changes anything.