Depends on what state you are in and where the items are sold whether you need to pay sales tax. Several states have proposed legislation to charge sales tax on Internet retail sales and affiliate sales. Even if you do not collect tax on your website you may still be responsible for paying taxes on certain Internet sales. If we talk about digital sales and mobile applications markets, you get money for ios apps dowload, for instance, with already collected taxes. 

A supreme court ruling in 1992 Quill v. North Dakota stated that retailers with an online business that had a physical location such as a store, office or warehouse in a particular state must collect sales tax from it's customers in that state. If a business did not have a physical location in a state where a sale was made then no sales tax would be collected on that sale. This ruling was first applied to catalog and mail order companies but has been revised to include online retail merchants.

When a consumer buys an item from another State whether it be in a store or online they are suppose to pay what is called "Use Tax" on their tax form that is due each April. So if you go across state lines to purchase a refrigerator and they don't charge you tax you are suppose to claim the tax amount when you file your taxes. Only one problem, nobody pays those taxes and State tax collectors are looking for was to collect these taxes that are not paid. With declining revenues State government can bring in millions of tax dollars to their budget by taxing internet sales so you can see why States are pushing hard for a national sales tax legislation to be passed.

Check with your local Secretary of State (SOS) to determine if you should be collecting State Sales Tax. The SOS office in your state can help answer questions about State taxes and if and how much you should be collecting.