Best way to increase listing selling price?

I have two items that sell for around 14.99 and 25.99. I had a low competitive price for years but it’s time for a $1 increase on both items. I am the only seller and brand owner.

Is it better to make multiple small increases gradually, like $0.25-0.5 or make one change of $1? Obviously I don’t want to hurt the algorithm and all that.