I have not had any issues with this. The value is still 13 places including both sides of the decimal place. You can look at the properties of SD5 (whatever the symbol is after the sketch is closed), and you will see it rounds display, but the value is still 4.285714285714 (or close to it).
The only time I found Creo rounding a calculation value is in the tab dialogs. You have to go back and edit the associated dimension property to get it to a finer precision by entering the fractional value again. This is very problematic to me but if you are aware, it is manageable.
I'm going to suggest there is another issue here that has the sketch trying to do something it doesn't want to do. I have had nothing but trouble with angles when it comes to reaching 0 degrees. It just cannot quite get there. but if you change the references to be equivalent at say 90 degrees, it has no trouble whatsoever. I run into this over and over again and just cannot quite capture it for a bug report. I know R&D has got to be aware of it as it is quite pervasive.