He added the three titles as coach to three he had earlier won as a player for the same side.
Robertson told SKY Sport after the latest success that defence won it again and was a repeat of the two earlier playoff games.
"It feels like the last three weeks have been finals for us. Last week [against the Hurricanes] felt like a final for us and we played a different team tactically but the side had adjusted well to the different style of the Jaguares.
"We talked about playing one pass footy or no pass and kick. Let's get boring let's go old school," he said.
Robertson said the game had demonstrated prop Owen Franks' ability. They felt they hadn't got a lot at early scrums from referee Jaco Peyper but when Franks found a little bit of rhythm and gained his first scrum penalty it was pure Franks.
"He's just got one of the greatest shoulders in the game and the second shoulder into the tackle and to do what he has done – they said have an operation and be out for six months, and he's come back in three and played like that, he is world class," he said.
Robertson said the side would spend around an hour in the dressing room in celebrating, but also acknowledging the departing players with their families because when they left the changing room it was the last time the team would be together.
Flanker Matt Todd, whose turnover created the only try of the game for hooker Codie Taylor said the side had talked throughout their week of preparation of trying to find ways to make key plays.
"We knew we had to front, especially the pack because they had big ball runners and if they get a roll on it's a tough night and they get quick ball so we had to front up and be good at the breakdown to slow their ball down.
"In the first 20 [minutes] we were probably guilty of trying to play too much but we managed to adjust and played a simple game. It probably wasn't the most exciting but in conditions like this it's just about doing the basics and doing them well.
Having the scrum produce key ball, especially when deep on defence had been satisfying. The scrum was one of their weapons and it was good in a final that they were able to turn to that at crucial times.
They were also mindful of not repeating their mistake against the Hurricanes in the semifinal of letting them get ball too quickly, for which they had punished the Crusaders.