Hi everyone,
We’re experiencing a rounding issue with taxes in our Shopify store and would like to know if there’s any way to configure or work around this behavior.
Scenario:
When we send order data to Shopify, we include the tax amounts per line item using up to 4 decimal places (e.g., 1.0156). If we sum all these tax values ourselves using full precision and round only the final total, we get the correct expected value. However, Shopify seems to round each line item tax to 2 decimal places before summing, which can result in a 1 cent discrepancy, either over or under.
We understand this is Shopify’s standard behavior, but it causes mismatches when reconciling totals with our system.
Example where Shopify ends up charging 1 cent more:
Let’s say we have 3 line items with tax amounts of 1.0142, 1.0142, and 1.0156.
The precise total, when summed without rounding, is 3.0440, which rounds to 3.04.
However, Shopify rounds each line item individually:
- 1.0142 → 1.01
- 1.0142 → 1.01
- 1.0156 → 1.02
Then sums them: 1.01 + 1.01 + 1.02 = 3.05
So we end up with a 1 cent difference, with Shopify charging more than the accurate total.
This also happens with item pricing:
We have a promotion where, in some scenarios, we calculate an average unit price across multiple items.
For example, if a user buys 9 items – the first 4 priced at 5.99 and the remaining 5 at 12.99 – the total is:
(4 × 5.99) + (5 × 12.99) = 88.91
88.91 ÷ 9 = 9.8789
If we send a unit price of 9.8789 for quantity 9, Shopify will round the unit price to 9.88.
Then: 9.88 × 9 = 88.92, resulting in a 1 cent overcharge compared to the actual total.
Questions:
- Is there any way to configure Shopify to round only after summing all line item taxes or prices?
- Has anyone found a workaround or best practice to avoid these discrepancies?
Thanks in advance for any ideas or suggestions!