IRoundingService is not available

[RomanSpeak]

Which component is this issue related to?

Umbraco Commerce (Core)

Which Umbraco Commerce version are you using? (Please write the exact version, example: 10.1.0)

13.2.3

Bug summary

The Umbraco Commerce patch notes mention the availability of the IRoundingService, which should have been implemented as a result of #506. It seems that this service is not exposed, nor is there any documentation about this particular service.

Specifics

We have a very specific rounding presentation scenario that we would like to resolve. It is attached as a separate .txt in case you're curious.

Issue description rounding unit and line.txt

Using the IRoundingService was also the suggestion of the support bot.

Steps to reproduce

Try creating a service that implements the IRoundingService

Expected result / actual result

No response

Dependencies

No response

[mattbrailsford]

Hi @RomanSpeak

So the IRoundingService wasn't implemented in v13 it was only in v15+ I believe. For the reasons it was implemented it wasn't essential to be backported to v13. Instead, in v13 the rounding just takes place as part of the order calculation pipeline.

This said, 13.2.4 addresses some rounding issues so I would first off suggest you upgrade to this at the very least.

With your example, it's not entirely clear where you have the discounts apply (base price, unit price, line total?), but I will say it's not going to always be possible to round prices individually and get everything to add up.

If you are applying discounts at base/unit price that result in several decimal places and then not rounding till line total, those discount values won't be rounded. If you try to grab the discount values directly, these will remain in multiple decimal places. It's only when these are all added together at the line level that they are then rounded. At that point, they may not be directly divisible by the quantity to get back to a rounded individual discount level.

Ultimately individual discounts remain unrounded, and it's only prices TotalAdjustment that will be rounded to fully add up with the TotalWithoutAdjustments and Total.

[RomanSpeak]

Hello @mattbrailsford

Thank you for the clarification! I'll likely try updating to the latest version in the coming days in order to check if that changes anything. We have the discounts at line level in our use-case, and it's purely about the presentation of a singular unit-price.

At this point I think it might make the most sense to simply take the line price as the unit price if the quantity is equal to 1. Might have to double-check what it looks like with different quantities or if the current logic suffices for that.

[mattbrailsford]

I'm going to close this bug as I think my explanation answers the initial question, but feel free to post back if you find out details that point to a calculation error and we can re-open / create another issue for your findings.