If it's a tangle thing (e.g. physical), then you have to pay sales tax on it once sold. The only exception if what you are selling is for resale and the person you sell it to has a resellers license.
Of course, the government needs to know that you actually sold something in order to collect the taxes. This is usually done via a business license or holding a resellers permit. If you don't have those things, then it will be a challenge for them to collect sales tax from you.