BO - Retail price & price per unit (tax included) are converted when applying the tax

[khouloudbelguith]

Prerequisites

• I understand and accept the project's code of conduct
• I have already searched in existing issues and found no previous report of this bug.

Describe the bug and add screenshots

Previously reported here: #26762 (comment)
Retail price & price per unit (tax included) are converted when applying the tax

For more details please check the comment of @jolelievre
#26762 (comment)

Expected behavior

No response

Steps to reproduce

Enable Experimental product page
Go to BO > Catalog > Products page
Add product V2 > in the pricing tab > change Tax rule to 10%
set the Retail price (tax incl.)= 500 & Retail price per unit (tax incl.) =500
Click outside
See error => it will be converted to 500.000001

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Enable Experimental product page
Go to BO > Catalog > Products page
Add product V2 > in the pricing tab > change Tax rule to 5.5%
set the Retail price (tax incl.)= 15 & Retail price per unit (tax incl.) =15
Click outside
See error => it will be converted to 14.999999

PrestaShop version(s) where the bug happened

1.7.7.8, develop

PHP version(s) where the bug happened

7.3

If your bug is related to a module, specify its name and its version

No response