(a) Every retailer of cannabis, whether or not the retailer has obtained a certificate of registration under Section 65-20, shall keep complete and accurate records of cannabis held, purchased, sold, or otherwise disposed of, and shall preserve and keep all invoices, bills of lading, sales records, and copies of bills of sale, returns, and other pertinent papers and documents relating to the purchase, sale, or disposition of cannabis. Such records need not be maintained on the licensed premises but must be maintained in the State of Illinois. However, all original invoices or copies thereof covering purchases of cannabis must be retained on the licensed premises for a period of 90 days after such purchase, unless the Department has granted a waiver in response to a written request in cases where records are kept at a central business location within the State of Illinois. The Department shall adopt rules regarding the eligibility for a waiver, revocation of a waiver, and requirements and standards for maintenance and accessibility of records located at a central location under a waiver provided under this Section.
     (b) Books, records, papers, and documents that are required by this Article to be kept shall, at all times during the usual business hours of the day, be subject to inspection by the Department or its duly authorized agents and employees. The books, records, papers, and documents for any period with respect to which the Department is authorized to issue a notice of tax liability shall be preserved until the expiration of that period.