diff --git a/CHANGES.md b/CHANGES.md
index 9c38282..6455edb 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,6 +1,7 @@
 # Changes
 
 ## Unreleased
+- Add splitBill(items, people) to split the taxed total into per-person shares.
 
 ## 1.2.0
 - total() rounds through roundCents().
diff --git a/src/lib/cart.js b/src/lib/cart.js
index 385fd69..bb38bb5 100644
--- a/src/lib/cart.js
+++ b/src/lib/cart.js
@@ -8,3 +8,16 @@ export function subtotal(items) {
 export function total(items) {
   return roundCents(subtotal(items) * (1 + TAX_RATE));
 }
+
+// Splits the taxed total between people (a count or an array), in whole cents.
+// Leftover cents go one each to the first people, so shares always sum to total().
+export function splitBill(items, people) {
+  const n = Array.isArray(people) ? people.length : people;
+  if (!Number.isInteger(n) || n < 1) {
+    throw new RangeError("people must be a positive integer or a non-empty array");
+  }
+  const cents = Math.trunc(total(items) * 100 + 0.5);
+  const base = Math.trunc(cents / n);
+  const extra = cents - base * n;
+  return Array.from({ length: n }, (_, i) => roundCents((base + (i < extra ? 1 : 0)) / 100));
+}
diff --git a/tests/lib/cart.test.js b/tests/lib/cart.test.js
index 7a9eab3..a4eed3b 100644
--- a/tests/lib/cart.test.js
+++ b/tests/lib/cart.test.js
@@ -1,6 +1,6 @@
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
-import { subtotal, total } from '../../src/lib/cart.js';
+import { subtotal, total, splitBill } from '../../src/lib/cart.js';
 
 const items = [{ price: 10, qty: 2 }, { price: 5, qty: 1 }];
 
@@ -11,3 +11,39 @@ test('subtotal adds price times quantity', () => {
 test('total applies tax and rounds to cents', () => {
   assert.equal(total(items), 27);
 });
+
+const sum = (xs) => Math.round(xs.reduce((a, b) => a + b, 0) * 100) / 100;
+
+test('splitBill splits the taxed total evenly', () => {
+  assert.deepEqual(splitBill(items, 3), [9, 9, 9]);
+});
+
+test('splitBill accepts an array of people', () => {
+  assert.deepEqual(splitBill(items, ['a', 'b']), [13.5, 13.5]);
+});
+
+test('splitBill gives one person the whole total', () => {
+  assert.deepEqual(splitBill(items, 1), [27]);
+});
+
+test('splitBill distributes leftover cents so shares sum to the total', () => {
+  const one = [{ price: 10, qty: 1 }]; // total 10.80
+  const shares = splitBill(one, 7);
+  assert.equal(shares.length, 7);
+  assert.equal(sum(shares), total(one));
+  assert.ok(Math.max(...shares) - Math.min(...shares) <= 0.01 + 1e-9);
+});
+
+test('splitBill gives extra cents to the first people', () => {
+  assert.deepEqual(splitBill([{ price: 0.1, qty: 1 }], 4), [0.03, 0.03, 0.03, 0.02]); // total 0.11
+});
+
+test('splitBill of an empty cart is all zeros', () => {
+  assert.deepEqual(splitBill([], 3), [0, 0, 0]);
+});
+
+test('splitBill rejects invalid people', () => {
+  for (const bad of [0, -1, 1.5, NaN, [], undefined, '3']) {
+    assert.throws(() => splitBill(items, bad), RangeError);
+  }
+});