[phenol]

IIRC, the whole "99 cent pricing" paradigm originated not as a method to subtly reduce the apparent price of products, but as a way to force cashiers to give change for all purchases, and thus open the register so that all transactions could be recorded.

Of course, this practice is completely obsolete in online shopping, while the psychological pricing effect remains.

[schrodingersCat]

This is apparently a subject of debate (see: http://skeptics.stackexchange.com/questions/2359/the-origin-...)

Most sources agree that its origins are in psychology, though your theory may explain its widespread adoption by retailers:

http://www.helium.com/items/705308-the-history-of-odd-retail...

http://www.eurekalert.org/pub_releases/2011-09/ru-9pm090611....

[smartwater]

Making it harder for employees to pocket the cash and pretend the transaction never happened, one of the most common techniques used by cashiers to increase their hourly wage. Just thought I'd explain a little bit more for anyone who still didn't get it.

[BuddhaSource]

Exactly my point, in online shopping pricing it .99 has any affect globally? I am very curious.