The Indian team crushed South Africa by 73 runs in the fifth ODI of the ongoing six-match rubber to take a winning lead of 4-1.
South Africa won the toss and elected to bowl first, but were unable to make any early in-roads as Dhawan and Sharma put on 48 runs for the first wicket.
Success in the series has lifted India above South Africa in the ICC's one-day rankings and they retain their No.1 status in Tests as well despite losing 2-1 last month to South Africa.
Rohit (115) who notched up his 17th ODI century hit 11 boundaries and four sixes in his 126-ball innings.
Hashim Amla scored a trademark 71 at the top of the order for South Africa and opening partner and captain Aiden Markram looked good for his run-a-ball 32. "India have a fantastic team, very well led by Virat Kohli, and they will continue to get better", added Hussey after the conclusion of the St Moritz Ice Cricket event.
The first ODI to be played at this ground was between India and South Africa in December 1992, where the hosts emerged victorious by 6 wickets.
For the Proteas, Lungi Ngidi was the pick of the bowlers.
No. 4 batsman Ajinkya Rahane was the second run-out victim, playing a ball to mid-on fielder and nearly reaching the other end of the pitch before realising Rohit was refusing a run.
On the tour so far, Rohit had tallied 118 runs in eight innings across two Tests and four ODIs.On Tuesday, he nearly doubled that at St. George's Park. Ngidi would later get MS Dhoni and Shreyas Iyer too.
He was shaky at times but the customary elegance was there to be seen as he stepped out to hit Kagiso Rabada over long on for a six. And the introduction of spinners, JP Duminy and Tabraiz Shamsi, also slowed down India's scoring rate in the middle overs.
Kohli and Rohit ensured India had yet another fruitful second-wicket association, putting on 105 in 109 balls, though Kohli never kicked into dominant gear, as only two fours in his 54-ball 36 showed.
Virat Kohli is arguably the most consistent and successful batsman across all the three formats of the game.
Klaasen, the other hero from the previous ODI, fought gamely with a 42-ball 39 but he was left with too much to do while running out of partners.