Whole cents, no rounding left over.

Splitting one cost

A cost is split by shares. "Equally" gives everyone ticked 1 share; "by shares" lets you give someone 2 (a couple) or 3. Each person first gets their share rounded down to the cent. The cents left over are handed out one at a time to the people whose exact share was cut the most; when that is a tie, they go in the order people were added to the tab.

Example. $100.00 for three people: each exact share is 3,333.33... cents. Everyone gets $33.33, which leaves 1 cent. It goes to the first person added: $33.34 + $33.33 + $33.33 = $100.00.

Balances

For each person: what they paid, minus their share of everything, plus paybacks they sent, minus paybacks they received. A plus balance means the group owes them; a minus balance means they owe the group. The balances on a tab always add up to $0.00.

The payback plan

The person who owes the most pays the person who is owed the most, as much as one of them needs; then the next pair, until everyone is at $0.00. With N people who are not square, that takes at most N - 1 payments, and usually fewer. When you tick "Mark paid" the payback is saved as an entry, so the plan updates for everyone.

A receipt (Check Splitter)

Each item is split among the people ticked for it (nobody ticked means everyone). Tax is the amount printed on your receipt, shared in proportion to each person's items. A tip in percent is worked out on the item total before tax and rounded to the nearest cent; a tip in dollars is used as typed. Both are shared like tax, so a person who ordered twice as much pays twice the tax and tip.

Why tax from the receipt? Sales tax depends on where and what you bought, so the site does not guess a rate. The receipt already has the right number.

What the site does not do

It does not move money, hold money, remind anyone by email or text, or decide what is fair for your group. It does the arithmetic, the same way every time.