Nathan edged fellow American Jay Bowman-Kirigin to capture his second World Cup moguls title of the season. Japan's Yugo Tsukita was third.
Roberts, who finished with a score of 25.78, also won at Deer Valley Resort in January.
Australian Dale Begg-Smith, who leads the World Cup standings with 384 points, was fourth.
Heil widened her lead in the women's standings with her third straight moguls win. American Michelle Roark finished second followed by Canada's Stephanie St. Pierre.
Heil now has 484 points, 147 ahead of American Shannon Bahrke who finished 14th Saturday.
The three-day meet finishes Sunday with the men's and women's dual moguls races.