Xerox said it has chosen Ted Bates Worldwide, as its new advertising agency to handle its corporate and business systems group in the U.S. . . . Merrill Lynch & Co said its retail stock brokerage unit plans to raise commissions an average of 5% on stock and options trades of less than $10,000 . . . Citing the rising Japanese yen, Toyota reported that it increased the price of its cars and trucks sold in the United States by 2.8%.