Bookstore sales are picking up momentum as the industry enters the holiday season. After posting a 5% sales gain in August, bookstore sales rose 6.7%, to $1.22 billion, in September, according to preliminary estimates from the Census Bureau. The gain in bookstore sales outpaced the increase for all retail sales, which rose 4.4% in September. For the first nine months of the year, bookstore sales were up 3%, to $9.33 billion.