This varies by state. This blog post provides more details on the sales tax requirements for each state.
GUIDANCE WARNING: Please note that the above guidelines do not constitute tax, legal, or other professional advice and must not be used as such. It is the sole responsibility of all Prodigi clients to comply with all legal and sales tax requirements for issuing sales tax or VAT invoices in respect to your sales transactions. If you are unsure as to what the contents of an invoice you issue to your customers should be, we suggest that you contact your tax advisor. Prodigi cannot assist you with any legal or tax advice as we’re not accountants or legal experts, and we stress that none of the above may be taken as professional advice.