Pemptus: Cheap marketing trick or not, it still works. It takes a second for the brain to process the .99c, and that second could mean the difference between a sale and no sale.
Brains are silly things.
Yep, especially on the number of digits changeover.
$5.99/$6.00? Still works, but not as much so.
$9.99/$10.00? Works wonders on a large portion of people, at least Americans. Why? The number of digits makes $10 seem like it's 'so much more'. Someone might say "Man, no way am I spending TEN DOLLARS! on that!" but for the same thing be like "Dude, this is only nine bucks!" >.> I've seen it happen.
It's not the worst marketing trick though..
Sale prices for merely a fraction of the regular price, or the regular price simply being listed as a sale price.. simply because people will see 'sale' and think "I'm saving money, and I don't have time to think about it rationally because there's a sale and it might end."
Us rational human beings, who actually take the time to weigh the pros and cons of a purchase.. are not the target audience of these tricks, they know we will buy based off of rational decisions. Impulse shoppers are the ones the tactics target. ;)