Actually, while not a lawyer, I do that that it does vary from state to state. Some states specifically make you show the sales tax as a seperate item, no matter what. Others, couldn't care less, as long as they get their pound of flesh.

But, if you are selling on the internet, you are only liable to collect taxes when shipping or delivering within your own state. Sales shipped elsewhere, even if ordered in your state, are not subject to sales tax. So, by including sales tax in your regular price, you would be raising the selling price unnecessarily for folks in the other 49 states.

And you need to check with your own state's department of taxation, or whatever name it goes by, to find out wheter they allow bundling the tax into a final figure, or required it to be shown seperately.