This is exactly right. It's an old marketing trick, plays into your initial reaction with the price tag. And often times people will round it down instead of up, so $99.99 will be $99 dollars, saying "Man, I got this awesome painting for my wall, it was only $99" sounds more appealing than "Man, I got this awesome painting for my wall, it was only a hundred bucks".

Actually, it started as a bookkeeping method but I don't recall how it works. If a retailer added up all his sales at the end of the day, or during the transaction, it should always end in a certain way. Odd/even? Don't recall but that's the root of the idea.