Charm Pricing Effect

Charm pricing is also known as psychological pricing. It's the belief that a price can have a psychological impact. Retailers can then use that psychological influence to sway customers to buy their products or perceive them a certain way.

Example: In an experiment conducted by the University of Chicago and MIT, women's clothing was used to test the left-digit effect. First, prices were set for $34, $39 and $44. To the amazement of the researchers, the items sold best at $39 even though that price was more expensive than other options.

Subset of Psychological Pricing (source):