I believe if sales rise to above a certain dollar amount in a year, business must charge tax.
"On June 21, 2018, the United States Supreme Court fundamentally changed the rules for collection of sales tax by Internet-based retailers. In its decision in South Dakota v. Wayfair Inc., the Court effectively stated that individual states can require online sellers to collect state sales tax on their sales. This ruling overturns the Court's 1992 decision in Quill Corporation v. North Dakota. The Quill case prohibited states from requiring a business to collect sales tax unless the business had a physical presence in the state."