A method and apparatus are disclosed for facilitating coinless transactions by rounding a fractional transaction cost up or down to a whole-unit amount. A fractional transaction cost is rounded up or down to a whole-unit amount based on a generated random number that ensures fairness to both buyers and sellers, over time. If a transaction purchase price is N.C units, where N is any non-negative integer and C is an integer between 0 and 99 indicating the fractional cost between 0 and 0.99, then a buyer will be charged N+1 units with a probability of p equal to C/100 and N units with a probability of 1-p. The random number generation process can ensure that the rounding process does not favor buyers or sellers, for example, by (i) incorporating a buyer-provided offset, or (ii) having the generation of the random number performed or supervised by a trusted third party. The buyer can increase his or her odds of having the final purchase price rounded down by exposing more than just the amount by which the rounded up cost exceeds the fractional cost.