Lateral Thinking.

"Many shops have prices set just under a round figure, e.g. $9.99 instead of $10.00 or $99.95 instead of $100.00 . It is assumed that this is done because the price seems lower to the consumer. But this is not the reason the practice started. What was the original reason for this pricing method?" I am very tempted to just leave it to provoke lateral thinking. Haha! Due to the current heat waves reported from many hot places around the globe, I rather provoke nothing and leave it up to the reader to peek or not. A lot of seemingly hard riddles with rather logical answers can be found here. Including a very simple answer to the question above...