Answer:
Round off to closest value.
Explanation:
In order to remove the requirement for change, every time the client buys a product for $0.20 the random number that lies between 0 and 1 would be produced also the same would be rounded to the closest value i.e. 0 or 1. In the case when 0 arise so the customer would not have to pay any amount but if 1 arise so the customer have to pay $1. So this type of method would remove the requirement for a minor change