If, after concluding a deal, you try to pay with a credit card, he may then boost the price in order to cover the card charges.
He may increase the price to cover the charge because he's dishonest.
mnli hypothesis: He may increase the price to cover the charge because he's dishonest. premise: If, after concluding a deal, you try to pay with a credit card, he may then boost the price in order to cover the card charges.