Does something costing \$9.99 really seem cheaper than \$10 to people?

I've always hated seeing prices like this. It makes me immediately distrust the seller. I wish all prices would be "even", such as \$250 instead of \$249.98 or whatever. To me, it does not look cheaper. Not even subconsciously. It just makes me annoyed every time I see it. I know that people in general are dumb, but I still deeply question this practice.

Do stores sometimes make tests where they change all their prices to round numbers for a while and then compare their sales during that time to their normal sales? And does it then really show that more people buy things because they use these "silly" prices?

• Interesting question. We normally expect some minimal research to back up your question, but given that this is such a widespread practice I think we can make an exception. Here is one interesting link: Fact or Fable: The Pricing Power of 9 Dec 13, 2021 at 16:03
• This link could be good "initial research" to base your question on: livescience.com/33045-why-do-most-prices-end-in-99-cents-.html Dec 13, 2021 at 16:05
• Not that related but I remember that 15 years ago or so it wasn't common practice in most European countries, so there has to be a reason why stores adopted this practice I guess? Dec 14, 2021 at 16:56