Tennessee Code Title 5. Counties § 5-14-105

(1) Contract for and purchase all supplies, materials, equipment and contractual services required by each and every official, agency, office, department or employee of the county government, or that is supported by, or under control of, the county government and that expends or encumbers any of the county's funds. No other official, employee or agent of the county or of any of its departments or agencies shall be authorized to contract for or purchase any such materials, supplies, equipment or contractual services;

(2) Arrange for the rental of machinery, buildings or equipment when the rents are to be paid out of funds belonging to the county or any department, institution or agency thereof; and no other official, employee or agent of the county shall have the right or power to make any contract for such rental;

(3) Transfer materials, supplies and equipment to or between county departments and agencies as may be needed for the proper and efficient administration of the county government; and

(4) Have charge of any central storeroom or central mailing room or similar services that may hereafter be established for the efficient and economical handling of the county's business.