Issue with Coupon Discount Rounding in WooCommerce Orders

Hello,

I am encountering an issue with coupon discount rounding in WooCommerce orders. We have set up multiple coupons that apply discounts based on product categories. While the discounts generally work correctly, there are small discrepancies in the final discount amounts applied to products. For example, two products with the same price and the same discount sometimes show a 1 cent difference in the final discount applied.

Here is an example from an order:


33007 - 8
Product ID: 33007
Variation ID: 17997
Size (Children): 8
Price: €6.99 × 1
Discounted Price: €5.59
Discount: €1.40
Final Price: €0.95

33006 - 6
Product ID: 33006
Variation ID: 17895
Size (Children): 6
Price: €6.99 × 1
Discounted Price: €5.59
Discount: €1.40
Final Price: €0.95

33005 - 4
Product ID: 33005
Variation ID: 15557
Size (Children): 4
Price: €6.99 × 1
Discounted Price: €5.60
Discount: €1.39
Final Price: €0.95

33005 - 10
Product ID: 33005
Variation ID: 15560
Size (Children): 10
Price: €6.99 × 1
Discounted Price: €5.60
Discount: €1.39
Final Price: €0.95

We have checked the following:

Decimal Places: Set to 2 in the WooCommerce settings.
Coupon Settings: Coupons are set correctly and apply based on product categories and payment methods.
Plugins: We have deactivated multiple plugins to check for conflicts, but the issue persists. Key plugins that cannot be deactivated include WooCommerce Extended Coupon Features FREE and WP Mail SMTP.
We are using the following setup:

WooCommerce Version: 9.1.1
PHP Version: 8.1.29
Server: nginx/1.26.1
WordPress Version: 6.5.5
System Status Report: Click to view

<details><summary>System Status Report</summary>

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τον/την weDevs – 1.14.5<br>Advanced Order Export For WooCommerce: απ? τον/την AlgolPlus – 3.5.3<br>WooCommerce Extended Coupon Features FREE: απ? τον/την Soft79 – 3.3.3<br>WP Menu Cart: απ? τον/την WP Overnight – 2.14.4<br>WooCommerce: απ? τον/την Automattic – 9.1.1<br>WP Mail SMTP: απ? τον/την WP Mail SMTP – 4.0.1<br>WP Super Cache: απ? τον/την Automattic – 1.12.3<br>WPForms Lite: απ? τον/την WPForms – 1.8.9.6<br><br>### Inactive Plugins (3) ###<br><br>Broken Link Checker: απ? τον/την WPMU DEV – 2.2.4<br>Duplicate Page: απ? τον/την mndpsingh287 – 4.5.3<br>WooPayments: απ? τον/την WooCommerce – 7.9.1<br><br>### Dropin Plugins () ###<br><br>advanced-cache.php: advanced-cache.php<br>maintenance.php: maintenance.php<br><br>### Must Use Plugins (1) ###<br><br>Index WP MySQL For Speed Upgrade Filter for mu-plugins.: απ? τον/την  – 1.4.17<br><br>### Settings ###<br><br>API Enabled: –<br>Force SSL: –<br>Currency: EUR (€)<br>Currency Position: right_space<br>Thousand Separator: .<br>Decimal Separator: ,<br>Number of Decimals: 2<br>Taxonomies: Product Types: external (external)<br>grouped (grouped)<br>simple (simple)<br>variable (variable)<br><br>Taxonomies: Product Visibility: exclude-from-catalog (exclude-from-catalog)<br>exclude-from-search (exclude-from-search)<br>featured (featured)<br>outofstock (outofstock)<br>rated-1 (rated-1)<br>rated-2 (rated-2)<br>rated-3 (rated-3)<br>rated-4 (rated-4)<br>rated-5 (rated-5)<br><br>Connected to WooCommerce.com: –<br>Enforce Approved Product Download Directories: ?<br>HPOS feature enabled: –<br>Order datastore: WC_Order_Data_Store_CPT<br>HPOS data sync enabled: –<br><br>### Logging ###<br><br>Enabled: ?<br>Handler: Automattic\WooCommerce\Internal\Admin\Logging\LogHandlerFileV2<br>Retention period: 30 ημ?ρε?<br>Level threshold: –<br>Log directory size: 90 KB<br><br>### WC Pages ###<br><br>Β?ση καταστ?ματο?: #1613 - /shop/<br>Καλ?θι: #1079 - /cart/ -  Contains the [woocommerce_cart] shortcode<br>Ταμε?ο: #1080 - /checkout/ -  Contains the [woocommerce_checkout] shortcode<br>Ο λογαριασμ?? 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</details>

Has anyone else experienced this issue or have suggestions for resolving it? Any help would be greatly appreciated.

I searched the forum for similar problems but didn’t find suitable answers.

Thank you!

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