SHOPRITE, South Africa's biggest supermarket group, reported on Tuesday a nearly 14% jump in its half-year sales, supported by a record Black Friday and festive season as cash-strapped shoppers and upmarket consumers went after food deals. The retailer, with more than 2,900 stores across Africa, said group sales for the six-month period ended December 31 rose to 121.1 billion rand ($6.44 billion). Sales in the company's second quarter, which include November and the Christmas holiday period, rose 14.6%. Cash-strapped shoppers, hit by high interest rates and inflation, are spending less on discretionary items like clothes and shoes and more on food and essentials. "Sustained…