How the vow­els in words are pro­nounced has an influ­ence on how we per­ceive the size of an item. This ‘pho­netic sym­bol­ism’ has also been shown to effect how we per­ceive prices:

Researchers have known for 80 years about a sym­bolic con­nec­tion between speech and size: back-of-the-mouth vow­els like the “o” in “two” make peo­ple think of large sizes, whereas peo­ple asso­ciate front-of-the-mouth vow­els like “ee” with diminu­tive­ness. Mar­keters can use this effect to make con­sumers think a dis­count is big­ger or smaller than it truly is. […]

In one exper­i­ment, researchers told con­sumers the reg­u­lar and sale prices of a prod­uct, asked them to repeat the sale price to them­selves, and then, a few min­utes later, told them to esti­mate the size of the dis­count in per­cent­age terms. Prod­ucts with “small-sounding” sale prices (like $2.33) seemed like bet­ter deals than prod­ucts with “big-sounding” sales prices (like $2.22).

In another exper­i­ment, the researchers used a pair of sale prices — $7.88, which sounds “big” in Eng­lish, and $7.01, which sounds “small” — but are the other way around in Chi­nese. Chi­nese and Eng­lish speak­ers had oppo­site per­cep­tions of the prod­ucts’ rel­a­tive value.

The authors of the study have also shown how, for dis­counted items, we per­ceive the dis­count on items to be larger when the right-most digit of its price is small (less than 5): the right digit effect.