Unequal bill split calculator

Shared charges land on each person in proportion to that person's item subtotal, and every column is rounded to the penny with a largest-remainder pass, so the parts always sum to the bill exactly. The settle-up list pairs the largest debtor with the largest creditor repeatedly: it is a short set of payments, not a guaranteed minimum number of transfers, and when nobody has paid anything yet there is nothing to settle between people, only shares to pay. Money stays in this tab; nothing is uploaded. Amounts stay within ±1,000,000,000.