Hi,

Odoo should display prices inclusive of tax for all products, including combo products, when "Prices Include Tax" is enabled on the website. The behavior of showing combo product prices without tax until checkout is not the intended behavior. Potential causes include incorrect tax configuration on the combo product or its components, conflicting pricelist settings, theme or customization conflicts, JavaScript issues, or a bug in the Odoo version.

To troubleshoot, verify the tax configuration on the combo product and its components, check pricelists, inspect the website theme for overrides, disable custom modules, and check for JavaScript errors. Testing with a standard theme can help isolate theme-related issues. By systematically checking these areas, you should be able to identify and resolve the incorrect price display.

Reference:-

* https://www.odoo.com/documentation/19.0/applications/sales/point_of_sale/combos.html

* https://www.youtube.com/watch?v=bwlRvBiG8mg

Hope it helps