The question is: If you model a coin toss, where does the randomness stem from? In a computational model without artificial randomness, you should get perfectly repeatable results, no?
A computer model using a deterministic physics system would be completely aware of the initial conditions of each toss. You'd presumably want to introduce some randomness in those initial conditions (using e.g. a pseudorandom number generator) to simulate human coin tosses.
(Note: make sure to give them toes.)