Change Precisions to 4 to solve #10790

[jonashrem]

Change Precisions to 4 to solve #10790

Description

I changed the rounding precision in app/code/Magento/Directory/Model/PriceCurrency.php to 4, to avoid issues with rounding in some situations. See #10790

Fixed Issues (if relevant)

solves #10790

Manual testing scenarios

Download the Dump provided here #10790 (comment)
Install Magento and use this dump as Database
Add 2 of each Product A and B to you shopping card
Apply Code "100percent"
Total Order should be 0

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[jonashrem]

Can please someone more experienced have a look at this?

After my investigation, I think this is the only way to avoid the issue and as far as I can tell, this works, but it could break functionality somewhere else.

[orlangur]

Hi @jonashrem, although this change may fix some particular scenarios, it may break some other which work correctly now. Something more sophisticated and configurable is needed instead.

Please check #11006 (comment) for more details.

[jonashrem]

Hi @orlangur

I see, thank you for the feedback.