Hello @Kenness and thanks for your question. Whenever you create an item, whether it is a physical item or a digital item, you have the option to turn on/off sales tax for that item. You'll have to already have assigned a tax rate when you setup your account or site. Here is some more info on how to create tax rates.
I would also check with your State's sales tax office as to what items are, or are not, you are required to collect and remit sales tax. You may not need to collect sales tax for digital items, but I do not know. So I would double check with your taxing authority.
I hope this helps answer your question.
