Generosity, Gratuity, and the Kingdom of God

I haven't seen too many blog posts on this.  When I go out to eat at a place where there is a gratuity involved, I consider a gratuity to part of my expression to the kingdom of God in someone's life, especially if they give me good service.  Its part of my silent giving that I give to give glory to God and encourage hard work and service. 

My working base is 20%.  If you give me average or slightly below average service, I'll tip you 15%.