The state of Tennessee's annual sales tax holiday is held every year, beginning at 12:01 AM on the last Friday in July and ending at 11:59 PM on the last Sunday in July. The 2018 tax-free weekend begins at 12:01 AM on Friday, July 27 and ends Sunday, July 29 at 11:59 PM.
https://www.tn.gov/revenue/taxes/sales-and-use-tax/sales-tax-holiday.html
Source: TN Department of Revenue