Ensure correctness for calculateExpenses for decimals

[mikejensen0]

Ensure that no money gets lost, when splitting expenses, e.g., if someone paid 100, which should be split amongst 3 people, then they are to receive 33.33... from the two others, and this could be rounded as:

Person 1: 33.34
Person 2: 33.33
Person 3: 33.33

Which means one person gets scammed. Perhaps there could be kept track of who "overpays" such that over time, this would equalize.