California Code, Business and Professions Code - BPC § 22974

A retailer shall retain purchase invoices that meet the requirements set forth in Section 22978.4 for all cigarettes or tobacco products the retailer purchased for a period of four years.  The records shall be kept at the retail location for at least one year after the purchase.  Invoices shall be made available upon request during normal business hours for review inspection and copying by the board or by a law enforcement agency.  Any retailer found in violation of these requirements or any person who fails, refuses, or neglects to retain or make available invoices for inspection and copying in accordance with this section shall be subject to penalties pursuant to Section 22981.