$cost = 1456.22;
$limit = 1000.00;

function check_limit($total_cost, $credit_limit) {

	if ($total_cost > $credit_limit) :
		return 0;
	endif;

	return 1;

}

if (check_limit($cost, $limit)) :
// Продолжить закупки
print "Keep shopping!";
else :
print "Please lower your total bill to less than $".$limit."!";
endif;