When shopping in most African countries and in Europe you must pay a tax, known as Value Added Tax (VAT), on most goods which is much like sales tax in the United States. The difference is that the VAT is already included in the sales price and the rate of VAT varies from one country to another. The VAT typically accounts for 10% to 20% of the purchase price of merchandise.
Foreign visitors can apply for VAT refunds, depending upon the specific rules of the country. Foreigners may be entitled to get back all or a portion of the VAT paid, in the form of a refund, on merchandise that is exported from the country being visited, however a refund may not be claimed on VAT paid for services.
Typically you must ask prior to making your purchase to be provided with the necessary documentation for the VAT refund. This may be as little as providing you with the original receipt or can be as extensive as filling out an official government form and having it stamped, in most cases you must also provide your passport and airline ticket to prove that you are a visiting foreigner. Most countries require that each receipt submitted for refund reflects a minimum amount of expenditure. To claim your refund, upon departure, you will be required to show the items that you have purchased and the required documents to customs officials prior to checking in your baggage to prove that the merchandise is indeed leaving the country.
Countries do this to encourage tourists to make purchases to stimulate their economies. About 30% of countries with VAT will let you reclaim it on items you take with you when you leave. Most countries in Europe allow VAT refunds. Countries in Africa that I know currently allow VAT refunds include South Africa and Namibia.