After leading 30-23 at halftime, Darell Combs opened the second half with a 3-pointer to start an 11-0 Jaguars run for a 41-23 lead. Mason Archie II capped the run with a steal and two free throws after being fouled on a fast break.
Denver made five 3-pointers during a 17-7 spurt to pull to 55-44 and Joe Rosga cut it to single digits, 64-55, with 5:33 left, but Barksdale answered with a 3-point play.
Combs finished with 16 points and Matt O'Leary had 11 for IUPUI (8-13, 4-2 Summit), which topped 60 points for the first time in five series meetings.
The Jaguars made 69 percent of their shots (27 of 39), including 8 of 12 from 3-point range.
Rosga led Denver (10-9, 2-4) with 12 points.