Cueto (11-11) rebounded from a rough first inning to get the win in his last start of the season. He allowed five hits and four runs with four walks and six strikeouts in six innings.
"It was very important for me to finish at .500, but more important was the team to win the game," Cueto said through coach and interpreter Juan Lopez. "It was very important for me to finish strong. I had a dead arm at one time, and I'm happy I finished strong, and I'll relax for a month and then start working out."
Manager Dusty Baker considered at least a .500 finish key for Cueto, who went 9-14 last season.
"I think it's a psychological boost as much as anything," Baker said. "I gave him a goal this year of 15, and he was on pace for that before he ran out of gas right at the All-Star break. I give him the same goal for next year, and I don't see why he can't make it.
Duke (11-16) walked a season-high five, one short of his career high, while losing for the fifth time with just one win in his last seven starts. He gave up six hits and five runs with two strikeouts in five innings in what manager John Russell considered to be an uncharacteristic outing.
"He wasn't missing by too much, and when he was missing, he was missing down in the zone, which is the mark of a good pitcher," Russell said. "He wasn't sharp."
The Reds tied it in the second on Rolen's leadoff walk and Darnell McDonald's one-out double to left field. Duke walked three batters in the second to give him four in the first two innings, as many as he had in five September starts.
"Obviously, my fastball command wasn't very good," Duke said. "That led to the leadoff walk. I tried to limit the damage after that, but I worked behind in the count too much."
Rolen snapped the tie on Duke's first pitch with two outs in the third inning, hitting it 401 feet into the left-center field seats for his first home run in 51 at-bats since Sept. 9 at Colorado, and his third since being traded to the Reds by Toronto on July 31.
The Reds added to the lead in a three-run fifth. McDonald scored from third on a passed ball charged to catcher Jason Jaramillo, and Votto added a two-run double.
The Pirates' Delwyn Young hit a 388-foot shot into the right-field seats for his seventh homer in the sixth.
Cincinnati took a 7-4 lead in the sixth. Willy Taveras, pinch-running after Ramon Hernandez led off with a double, scored on Juan Francisco's pinch-hit double. Drew Stubbs sacrificed, and Francisco scored on Paul Janish' suicide squeeze.
Votto hit his 25th homer of the season -- an opposite-field 380-foot solo shot into the left-field seats -- in the eighth.
Duke finished 1-4 in five starts against Cincinnati this season ... Reds 2B Brandon Phillips snapped a 0-for-16 slump with an eighth-inning single to center field. ... Andrew Claggett pitched the eighth, becoming the 49th different player and 26th pitcher to play for Pittsburgh this season, tying franchise records for players and pitchers used in a season. The Pirates used 49 players in 1987 and 2001 and 26 pitchers last season. ... The Pirates set a franchise record with their 100th game of the season without an error.