Unlike value added tax, sales tax is imposed only once, at the retail level, on any particular goods. Nearly all jurisdictions provide numerous categories of goods and services that are exempt from sales tax, or taxed at a reduced rate. Purchase of goods for further manufacture or for resale is uniformly exempt from sales tax. Most jurisdictions exempt food sold in grocery stores, prescription medications, and many agricultural supplies. Generally cash discounts, including coupons, are not included in the price used in computing tax.