Sales through bookstores rose for the fourth consecutive month in May. According to preliminary estimates from the U.S. Census Bureau, bookstore sales in May were up 4%, to $905 million. Sales for the entire retail segment increased 5.2%. Bookstore sales for the first five months of 1998 rose 1.0%, to nearly $5 billion. Despite the four straight months of improved sales, the bookstore market is still recovering from a weak January, when sales fell 9.5%.