Report: Wal-Mart food prices going up

Wal-Mart and Whole Foods -- the nation's lowest- and highest-priced big grocers, respectively -- have inched a little closer together.

Wal-Mart, despite launching an aggressive marketing campaign this month touting its price cuts, or "rollbacks,"on supermarket items, has actually raised its prices on food by 2.3 percent since February, according to a new study by JPMorgan Securities.

Meanwhile, Whole Foods has stuck with a price-cutting strategy, lowering its prices by about five percentage points since December vs. mainstream grocers like Kroger and Safeway, the study found.