Three housemates
An example, with sample figures.
Rent at agreed, unequal shares, every month.

Everyone's share is set once, say 40, 35 and 25 percent, and each month's rent is recorded with it. Each housemate's page shows how what they owe adds up.
Remind someone who owes, or cover a small amount instead.
Worth knowing
Someone records the rent each month: nothing records itself. A bill shared differently is given its own shares.
Shared costs, in the docs