Does Verizon include tether data in its cellular network data count on the iPhone?

I have an iPhone 4S and I have the 2G data plan, so I'm getting a little worried that I've only had it for a week and a half and my phone is already saying that I've used 600 or so MB of "Cellular Network Data". I have Wi-Fi available at my home and I use that whenever available. I do check Facebook and other social networks relatively often away from home. However, the data counter on my phone lists nothing used under the "Tether Data" count, and I'm under the impression that this count should include Wi-Fi. So I want to confirm, am I really racking up usage on my 2G of data or is it including Wi-Fi and such and if so how can I find out how much data I have actually used on the plan? Please answer if you have any idea.

If you use your phone to connect to a Wi-Fi network than verizon will not charge you for the data you use while on that network