Sun, a first year from San Marino, and Rocha, a senior from Downey, shot 17-over 161 over two rounds.
Sun shot an outstanding first round with 77 and finished with an 84.
"It was outstanding to see Vivian play so well on Saturday," Oxy head coach Will Morris said. "This was some of her best golf of her young career and we're excited to see her continued improvement."
Rocha had rounds of 80 and 81.
"Sam was a steady force for us as she's been her entire career," Morris said. "She played very well on the front nine both days, which I believe is the tougher nine on this championship course."
Izzy Ruiz posted a 174 for 29th place and Anna Lundquist totaled 175 for 31st place, rounding out Oxy's scorers.
Claremont-Mudd-Scripps took first at the tournament with 609 and Caroline Ordian of Redlands was the low medalist.
Next Round: The Tigers are back in action at the three-round SCIAC Championships at Los Serranos on April 22-24.Follow Oxy Athletics on Twitter Sign Up for Newsletters Watch on Youtube Follow us on Instagram