The delivery tax these days is probably exclusively for gas. 20% tip for all deliveries because they pay delivery guys ass. One pizza delivery job I had paid $2.00/hr. Another I had paid $1.50 because the tips at that joint were really good. They were, but that's still a scary minimum wage. I'd rather have a better system, but having lived on that side of the fence a couple of summers, I do what I can for these guys.