I've had Danios, kuhli loaches and some shrimp jump, as well as a Betta. I have open tops too but I'm going to make screen tops for them, as it's too depressing to find a dried out fish or shrimp on the floor.
One Black Kuhli leaped from it's tank, and somehow managed to land in a shrimp tank that was below it, but well off to one side. Even if he jumped from the closest corner, he would have to have 'flown' at least 3 feet to get to where he ended up. So the screen covers are going on as soon as I can get them assembled.
They can be made so they are virtually invisible, if you use clear quarter inch mesh netting. Bulk Reef Supply sells it and kits to make common sizes, using the aluminum framing that's used to make screens for windows and screen doors.
Home Depot sells the necessary tools and materials too, but not the clear netting. It's not that costly really. The frames only come in brown and white but it's not difficult to paint them whatever colour blends in best with your setup.
But if you want wide open tops, you have to be prepared for the odd fish to decide a jump is a good idea.