Why Is My WooCommerce Subscription Total Off by a Few Cents?

Why This Happens

Floating-point currency math is inherently prone to small rounding discrepancies unless handled carefully, and WooCommerce itself offers a setting for whether tax rounds per line item or on the cart/order subtotal — the two methods can produce genuinely different final totals by a cent or two on certain combinations of prices and tax rates. Subscription-specific calculations (proration on a plan switch, or a synced billing date's partial-period charge) add another place rounding can happen slightly differently than expected.

Common Causes

• Tax rounding mode (per line item vs. per order total) under WooCommerce → Settings → Tax — switching this can itself change totals by a cent on some orders, so confirm which mode is actually intended and consistent.
• Proration calculations (switching plans, or the first charge under a synced billing date) doing their own rounding at an intermediate step, then combining with tax rounding in a way that compounds into a slightly different total than a simpler calculation would produce.
• Currency formatting/display rounding differing from the actual stored value — sometimes what looks like a calculation error is really just a display rounding difference between two places that should agree but format slightly differently.
• A third-party pricing or discount plugin performing its own rounding independently of WooCommerce's core tax settings, producing a result that doesn't reconcile cleanly with the rest of the calculation.

How to Trace and Fix It

1. Reproduce the discrepancy on a specific, repeatable order rather than trying to reason about it abstractly — note the exact line items, tax rate, and any proration or coupon involved.
2. Check the tax rounding setting and confirm it's set the way your accounting expects, since this is the single most common cause.
3. If proration is involved, manually calculate what the expected prorated amount should be and compare it against what the system actually produced, to isolate exactly where the difference is introduced.
4. Check any third-party pricing plugin's own rounding behavior if one is involved, since it may not follow WooCommerce's core settings at all.

A cent-level discrepancy is rarely urgent on its own, but worth resolving properly if it's happening consistently — see WooCommerce fixes for a proper trace.