the reason a penny is still here is the reason that its alway $19.99 or $99.99, 99.99 is really a hundred bucks, but when we see the 9's, we automatically think of it like 90, is a lot cheaper. It is done in order to make people want to buy things more. 19.99 makes people think of ten. But to do this method of commercialism, you would have to have a penny for change.
my mother always told me to look after all my change cause it adds up. I recently finished filling up a large bottled water jug and (long process though) so far I'm at 30$ and you really can't see much where the coins went down - I've got many hours of sorting and counting ahead!