LinearAxis - Unit Rounding

Original post:
https://oxyplot.codeplex.com/workitem/10156

How do I round unit on axis?
Example:

I have set.
Axis.FormatAsFractions = true;
Axis.FractionUnit = Math.PI;
Axis.FractionUnitSymbol = "π";

I do not 1,2755645656231456π but something like 1,276π.

Thanks for the answer

Setting StringFormat only works when Axis.FormatAsFractions is set to false.

This should now be fixed. A unit test that covers this case was also added.