I don’t really understand the “decent person” comment.

Left-digit bias is a default way that the human brain works.

Humans also tend to like fat, sugar, and salt. So, when you go to a restaurant if they add more butter to a recipe than you would at home are they unethical?

I agree with that strategy. Makes sense.

Yeah, if I want to sell something for $400 then I list it at $395 rather than $399.

I do not have the patience to deal with someone looking to haggle.

Not trying to start a debate with you and I know you’re just talking about a $10 item (and I agree with you on that) but your comment about “not looking to haggle” being the reason you’d use a whole number is not in agreement with another psychological trick.

When Negotiating A Price, Never Bid With A Round Number

I understand. But what if you’re selling a refrigerator or laptop for $400? You could list it for $399 or $395. The left-digit bias is not just pennies / cents. It applies when going from $99 to $100…$399 to $400…$999 to $1000 etc.

It’s not just pennies / cents. It applies when going from $99 to $100…$399 to $400…$999 to $1000 etc.

If you’re selling a car and you want $4000 for it then it’s best to list it for $3999 or $3995. Sure, you’re giving up $1 or $5 but you’re making that price look much more attractive due to the left-digit bias.

Fair enough. Upvoted!

If at any point left-digit bias stopped working then merchants would increase the price by a penny or a dollar (when going $99 to $100). Walmart is not going to leave money on the table. It still works.

That sounds a lot like when people say, “I’m not affected by advertising at all”. I am sure the effect has influenced some of the purchases in your life.

And even if you are 100% immune to it my point is about selling items to other people. You’re trying to get other people to buy the item you have for sale. Your brain rounding up does not allow you to take advantage of the well-known left digit bias which affects everyone in the world except you. So, if you round up when you sell an item you lose some advantage.