Curran and Adam Rossington (51no) got the County over line as they claimed a six-wicket win inside two days.
It was a good end to a disappointing season for Northants, who won just eight of their 36 matches in all competitions.
And Ripley said: “It was tight - we’ve been in that position before.
"The wicket was better than the first-innings scores suggested but you need somebody to get you over the line, and step up Ben Curran.
"It was a really mature innings and we were in dicey territory still needing 80 to win four down but Ben played well and had Adam Rossington to help him finish the game off.
"We said the right things about trying to finish well and we actually delivered it so that’s a pleasing thing.”
Sussex put Northants under pressure in their run chase, restricting the home side to 82 for four before they reached their victory target of 170.
And Sussex boss Jason Gillespie said: “We didn’t drive the game forward and we had the opportunity to after winning the toss on a good surface that just assisted the bowlers for the first 90 minutes of day one.
“To get bowled out for 118 you’re not driving the game forward and even though we bowled them out cheaply they still had a lead and we saw the wicket had got better to bat on.
“Second innings we showed signs but we weren’t able to drive home the advantage we created and it’s been like that for the last month or so.”