(2) The Governor General, subject to such conditions as he or she may prescribe, may authorise any person, other than a public officer, to sell adhesive stamps at any place other than an office in a public department; and the Governor General may order that a discount, not exceeding 5%, shall be allowed to any such last mentioned person authorised to sell stamps, on adhesive stamps of the total value of $15 purchased by him or her at any one time from a Postmaster.