Voters narrowly approved a sales tax increase to help fund a BART extension into the South Bay, the latest vote tally shows. With all but a handful of ballots counted, Santa Clara County's Measure B secured the necessary two-thirds approval needed to win. The count Friday was 66.78 percent in favor, enough for backers to finally claim victory after the proposal had been losing in the days after the Nov. 4 election. The plan calls for raising the Santa Clara County sales tax by one-eighth of a cent, revenue from which will help to operate and maintain the 16.1-mile extension...