Funny you just posted this and I just dropped one of my 1st books in a series from $3.99 to $2.99. This is the first book in a two book series. But I lowered my price on a standalone book a couple months ago and saw no change in sales. So that other book went back up to $3.99 last week.
For my books and genre, $3.99 USD is my average benchmark. Many others seem to hover around $4.99. And I bet inflation will drive things higher. I've never done $0.99 unless it's a promotion. I've never done permafree. But I might do these things in the future.
In another brand new book, I raised it to $4.99. Why? It's fantasy and the painted cover and editing and size were double the cost of my other books. Will I make the money back? I don't know. I can always lower it. But I truly believe it's worth $4.99. We'll see what readers think.
So, I'm yo-yoing prices, but I'm keeping an eye on them. A much shorter way of answering this is that I think you should feel free to experiment for a month or two and adjust accordingly.