Wal-Mart reported disappointing same-store sales on Tuesday, as many consumers chose not to spend their savings at the gas pump. The world's biggest retailer also said profit in its first quarter fell 7%, dragged down by currency fluctuations, investments in e-commerce and its plan to raise employee wages. Shares fell 2.5% to $78 in pre-market trading. On a call with investors, CEO Doug McMillion said: "We know that many of our U.S. customers are using their tax refunds and the extra money from lower gas prices to pay down debt or put it into savings." He added: "They're also using t...