Update significant figures on methods

[FranceJ]

Several methods currently are able to return repeating decimals or irrational numbers. We should either standardize the level of precision that our methods return or (better) add in an additional optional argument to specify the level of precision.

This would require updating several of the methods but seems necessary for users to have consistent results.

[BlakeGuilloud]

Is this something you could take on @FranceJ ? Or should it be broken out into several issues?