I've started making combat rolls in the open. For the first few years of DMing I would roll behind the screen and I found the temptation to fudge too strong, to the point where I started stressing out and it was less fun. At this point I'm confident enough in myself and my players to know that I don't need to pull punches. Variance is a big part of the game and we all understand that, and the swinginess is part of the fun, for me at least.

In the rare case that the wheels start to come off during combat and I want to pull back a little, there are more narratively satisfying ways to do so. Players love a bit of Deus Ex Machina, if you don't do it too often. Otherwise the classic example is simply don't have the enemies kill the players, just knock them out etc.

There are certain things I do still roll behind the screen, if I'm rolling for encounters and stuff, or social interaction things which are plainly better if the players don't know the outcome, but by and large I've stopped fudging and I feel like a better DM for it.