diff --git a/README.md b/README.md
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@@ -3,16 +3,15 @@
[](https://goreportcard.com/report/github.com/nmoniz/any2anexoj)
[](https://coveralls.io/github/nmoniz/any2anexoj?branch=coveralls-badge)
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+
+
+
This tool converts the statements from known brokers and exchanges into a format compatible with section 9 from the Portuguese IRS form: [Mod_3_anexo_j](https://info.portaldasfinancas.gov.pt/pt/apoio_contribuinte/modelos_formularios/irs/Documents/Mod_3_anexo_J.pdf)
> [!WARNING]
> Although I made significant efforts to ensure the correctness of the calculations you should verify any outputs produced by this tool on your own or with a certified accountant.
-> [!NOTE]
-> This tool is in early stages of development. Use at your own risk!
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## Install
```bash
@@ -24,3 +23,9 @@ go install github.com/nmoniz/any2anexoj/cmd/any2anexoj-cli@latest
```bash
cat statement.csv | any2anexoj-cli --platform=tranding212
```
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+## Rounding
+
+All Euro values are rounded to cents (2 decimal places) but internal calculations use the statement values with full precision.
+There are no explicit rules or details about how to round Euro values in Anexo J.
+This application rounds according to `Portaria n.º 1180/2001, art. 2.º, alínea c) e d)` (Ministerial Order / Government Order) examples, which imply we should round to the 2nd decimal place by rounding up (ceiling) or down (floor) depending on whether the third decimal place is ≥ 5 or < 5, respectively.