It's originated in America, it's also why you don't see things for sale for £700 or £800 but rather £699 and £799.
Your brain only sees the first part of the price, so you are more likely to buy the 699 over the 700 because you sub consciously think the 699 is substantially cheaper than the 700.
It's also why a lot of companies list extortionate prices as list prices but let you negotiate substantial "discounts" so you convince yourself you are getting a great deal.
When in fact, you are paying exactly what they wanted you to pay.