It is included on the dining plan. Sometimes people want to know how much the tax is on food in order to compare what their OOP costs would be in comparison to the dining plan.
That's exaclty what I was doing. Figuring what we would normally eat, with prices (on allears), then adding the tax. Because we are a party of 7, we'll be charged the 18% gratituty regardless.
By knowing what the tax % was, I was able to figure out the cost exactly, which makes my anal-retentive husband happy.
My husband and I decided to go with the Dining Plan. I'm not always a big eater, but I think if I saw all the prices for things I would be tempted to just eat the cheapest thing on the menu, which might be hotdogs and hamburgers. I don't want to eat that everyday of my trip. So we thought the dining plan was a good idea. It will give us the opportunity to eat different things without the guilt factor - because you already paid for it!
Depending on where you go for your CS and TS, you can save a lot. The greedy side of me wants to find all the expensive places and eat there so as to maximize the value of the plan.