Sec. 47. Transactions involving the sale of or the lease or rental of storage for:
(1) coins that are permitted investments by an individual retirement account or by an individually-directed account under 26 U.S.C. 408(m);
(2) bullion that would be a permitted investment by an individual retirement account or by an individually-directed account under 26 U.S.C. 408(m) if the bullion was in the physical possession of a trustee; or
(3) legal tender;
are exempt from the state gross retail tax.