I rarely order deliveries so I'm not sure if there's an etiquette. I'm talking abut companies where you don't have to pay any sort of delivery charge.
Also does it depend on whether you have paid online or if you are paying cash? In the past if I've paid cash I'll just tell them to keep the change if it's a small amount, but that's it. It never occurred to me till recently that you might be expected to give them a tip, so realised I might have been really stingy in the past (but then again pizza can be really expensive)
And actually passed?