I’ve made mine a bit more granular (and I often underprice for various reasons):
I’m following her lead on this in most respects, since I need this as a source of income and she’s obviously found a formula that works. I didn’t like the sudden jump from $0.99 to $2.99, so I added an extra price step in there, to make myself feel more at ease.
I try to keep the prices fair and also profitable.
Feel free to check out my work on Amazon and Smashwords: