One of the suggested reasons for prices ending in '.99' was to ensure that shop assistants in the Woolworths-type low price stores HAD to go to a till to get change, and could not pocket the cash!
(If it had been me, I'd of had a pocket full of pennies!)
But to take up the point about price RISES, before I retired from a company which made small springs and pressings seven years ago, our large company customers would demand something like a 5% REDUCTION in prices each year - on the basis that we should be improving our efficiency. They seemed to ignore rising material costs!