Why don’t my cart totals update when I change quantity or shipping?

Stale totals, subtotal, tax, or discount not refreshing when you change quantity, address, or shipping, come from a broken totals collector, a stale checkout-data / customer-data section, or a KnockoutJS component that isn’t subscribing to the totals observable. We repair the data flow so the displayed totals always match what the order will actually charge, and regression-test it across guest and logged-in carts.