Faced with a saturated market where just about everyone who wants a credit card has one, the companies have set their sights on what by one estimate is the $1.32 trillion in cash spent every year on purchases less than $5. Emboldened by consumers willing to download songs at 99 cents a pop or cell phone ring tones at $2 apiece, card companies are courting fast-food chains, taxicab companies and parking-meter manufacturers that have traditionally accepted only cash. Even American Express Co., whose cards are associated with expense accounts and luxury purchases, teamed up with PepsiCo Inc. to roll out credit card-accepting vending machines last year, mostly in casinos, malls and convention centers.

Visa and MasterCard -- joint ventures made of up of thousands of banks that issue credit and debit cards -- prohibit merchants from setting minimum payments. American Express, which issues it own credit cards, discourages minimums but allows them if the merchants apply the same limits to other cards they accept.

[Carl F. Pascarella] said he's confident that Visa can overcome resistance from merchants, as it did when it first rolled out credit cards decades ago, and then debit cards, which gained popularity in the mid-'90s and helped spur card transactions for low-value items.