Roberts scored 15 points with 11 rebounds and Kanacevic had 11 points and 14 rebounds.
Langston Galloway paced the Hawks (24-9) with 19 points and DeAndre Bembry scored 13. Saint Joe's assured itself a return to the NCAA Tournament for the first time since 2008, when it lost to Oklahoma in the first round.
Rob Brandenburg had 18 points and Treveon Graham scored 15 for the Rams (26-8), who played without A-10 Sixth Man of the Year Melvin Johnson.
Johnson suffered a knee injury early in VCU's semifinal win over George Washington.