Sales played his part in a superb bowling effort from Richard Dawson's side in Wednesday's quarter-final in Antigua.
The 18-year-old opened the bowling and claimed two for 33 from eight overs as South Africa were bowled out for 209 in 43.4 overs.
Leicestershire leg-spinner Rehan Ahmed led the way for England, taking four for 48, while Lancashire's Joshua Boyden finished with two for 31.
England were then indebted to a superb 88 from just 42 balls as they cruised to 212 for four with 18.4 overs to spare.
Sales was not required to bat, with Yorkshire's Will Luxton seeing his team over the line with an unbeaten 47.
England must now wait to discover who their semi-final opponents will be.
The three remaining quarter-finals see India take on Bangladesh, Australia square up to Pakistan and Afghanistan play Sri Lanka.
England will play their semi-final at the Sir Vivian Richards Stadium in Antigua next Tuesday (Feb 2), with the second semi-final a day later.
The final will also be held in Antigua on Friday, February 4.
This current crop of players are aiming to become only the second England team to win the competition, with the previous success coming back in 1998.
Involved in that tournament win were a trio of players very familiar to Northants supporters, with the winning team including former County men Stephen Peters, Graeme Swann and Richard Logan.
Peters, who was then a youngster at Essex, was named man of the match in the final win over New Zealand, as he scored a match-winning 107.