This is on purpose. Our brain associates for example 9.99 closer to 9 rather than 10, therefore pricing something at 9.99 is like pricing it as 10 but advertisi

This is on purpose. Our brain associates for example 9.99 closer to 9 rather than 10, therefore pricing something at 9.99 is like pricing it as 10 but advertising it as 9. It's pure and simple manipulation, which is what all sales techniques are based upon.