@trevordjones and @LWest0, I also don’t have a workaround solution without having access to custom coded actions…unless you want to go the really really manual route.
You can export your data to Excel, create a second column for your custom property and use the =TRUNC(number,[num_digits]) formula to generate your new value, then import it back to HubSpot.
As @danmoyle mentioned, if you can share your use case or more details, we can likely come up with a solution that could solve for the need in a different way.