How about a 20+% service charge and a delivery charge of $1-$2 on top of that, which I've seen.

Plus, if you compare, you'll see the same items on the room service menu that are in the restaurant are $1-$2 higher! Its all from the same kitchen.

And really you don't have the ability to "send it back" when the overcook your $13 hamburger.

Its an awkward situation when the give you the charges, there is an open spot for gratuity and he's waiting for you to complete. I've either added $1 or written "included" in that spot depending on my mood.