A group representing Amazon.com Inc, Facebook Inc and Alphabet Inc joined the U.S. Chamber of Commerce and others in filing suit on Thursday to challenge Maryland's first-in-the nation new digital advertising tax. The Chamber, the largest U.S. business group; the Internet Association, which represents dozens of tech companies; the Computer & Communications Industry Association; and NetChoice filed suit in U.S. District Court in Maryland seeking an injunction to block the new tax adopted last week by the state legislature over the veto of Republican Governor Larry Hogan.