The Iowa caucus bylaws state that when a vote is too close to count and/or there is a tie, the vote can be determined by a coin toss. In the case of Democratic candidates Hillary Clinton and Bernard Sanders a coin toss was used for at least six precincts.
And Clinton won all 6 coin tosses. The probability that anyone could win consecutively six coin tosses is only 1.6 percent. So, how did this happen?