The reason for prices ending in x99.99 is that some people, who are even more stupid than the guys that thought up this project, thinks that 99.99$ isn't even a hundred bucks, so that must be unbelieveably cheap for an object that costs 100$ in the shop next door.

In general, people who fall for this trick are in other words even more stupid than Those stupid ad execs who make every price end in 99.

It is a fact that people actually thinks that 49.99$ is much less than 50$, and therefor they buy more stuff that's only a nickle cheaper...