States will lose an estimated $4.41 billion in uncollected sales tax revenue due to retail e-commerce and catalog sales this year, and that figure that will grow to $6.84 billion by 2008, according to a University of Tennessee study, reports Internet Retailer. If taking B2B online sales into account, lost-tax-revenue figures would rise to $18-$22.81 billion this year and $21.54-$33.68 billion by 2008, according to the study.