The percentages vary on the product type for each product. Each product type (Settings > Product Types) is configured with a tax class. That's what determines the percentage and what taxes are assessed. So, Product A may have different taxing and percentages from Product B. As such, things like county, state, residential and business also contribute to what is taxed. So, a resident in Florida may have different taxes than a New York Business.
If you have a specific product that you're wanting to know more about, you can use the Tax Calculator (Home > Tax Calculator) and select the product, enter in a zip code, and view the taxes on it.