“…the average person treats a price ending in .99 as if it were 15 to 20 cents lower.”
The tendency is called left-digit bias, when the leftmost digit of a number disproportionately influences decision-making. In this case, even though the real difference is only a penny, research shows that, to the average person, $4.99 seems 15 to 20 cents cheaper than $5.00 – which results in selling 3 to 5 percent more units than at a price of $5.00"
The problem isn’t the effect, the problem is you don’t seem to understand what it actually does. The idea is to reduce the price in such a way that a small discount appears larger, increase sales, and make the reduction back in volume. It works, and makes sense, and is done, if and only if you compete on price and trade in volume.
Your title is, at the time of writing: “People live their whole lives watching corporations end prices with 99 yet when they list their own items for sale they choose a whole round number and never question it.” This thread is full of people giving you reasons why they don’t or wouldn’t do that, meaning they clearly do question it, and are deciding against it.