Proposed Internet sales-tax legislation received a huge boost on Monday when the White House officially backed the bill, saying it would level the playing field among online and retail stores by ensuring that both pay sales taxes. “Today, while local small-business retailers follow the law and collect sales taxes from customers who make purchases in their stores, many big-business online and catalogue retailers do not collect the same taxes,” White House press secretary Jay Carney. “This puts local, neighborhood-based small businesses at a disadvantage to big, out-of-state, online companies.”Now, the Senate is scheduled to debate the Internet sales-tax legislation for...