Business & farm

A couple of thoughts here:

• Obviously the state of Tennessee received something in order for them to contact you in regards to the sales.
• Have you reconciled your 1099-K?  Do these reconcile to what you would expect? 
• You should contact each of the marketplaces you sell on to get a handle of the procedure(s)
• Here is a link to provide some general guidance on this matter, but as @rjs indicated, this forum is geared toward income taxes and not sales taxes.
• https://www.tn.gov/revenue/taxes/sales-and-use-tax/out-of-state-dealers-marketplace-facilitators.htm...