Subject to the availability of funds appropriated under section 2027 of this title, the Secretary is authorized to formulate and administer a supplemental nutrition assistance program under which, at the request of the State agency, eligible households within the State shall be provided an opportunity to obtain a more nutritious diet through the issuance to them of an allotment, except that a State may not participate in the supplemental nutrition assistance program if the Secretary determines that State or local sales taxes are collected within that State on purchases of food made with benefits issued under this chapter. The benefits so received by such households shall be used only to purchase food from retail food stores which have been approved for participation in the supplemental nutrition assistance program. Benefits issued and used as provided in this chapter shall be redeemable at face value by the Secretary through the facilities of the Treasury of the United States.