Despite a struggling economy, bookstore sales rose 5.1% in the first quarter, to $4.46 billion, according to preliminary estimates from the U.S. Census Bureau. Sales have risen every month in 2008, although the March 1.3% gain was the smallest to date. Bookstore sales comparisons with a year ago have benefited from a weak first quarter in 2007, when sales were down 4% compared to the first period in 2006. Still, according to the Census Bureau, bookstore sales have done better than the overall retail segment, which had a 3.9% increase in the quarter.