I heard there was a second reason for pricing say 9.99 instead of 10.00. It forced the cashier to open the register and ring up the sale to give the 0.01 change

I heard there was a second reason for pricing say 9.99 instead of 10.00. It forced the cashier to open the register and ring up the sale to give the 0.01 change, rather than just quietly pocketing the 10.00. No idea how true this is, but it sounds plausible.