As long as you are selling to someone in your own state, and your state does not exclude state and local taxes on books, you have to charge buyers in YOUR state sales tax. All other buyers are exempt from sales tax according to what the state told me.
For eg. Anybody I sell to in IL has to pay 6.25% sales tax because that is what the sales tax rate is in my location. Outside of IL, I do not charge sales tax. Then, of course, you have to file a Sales Tax Return [called different things in different states] quarterly or yearly if your sales are not much.