When network fees are considerably low such as when working in s.devnet.rippletest.net the network fee throws the following exception: "Xrpl.Client.Exceptions.ValidationException: xrpToDrops: value '0.0000012' has too many decimal places." which traces back to here:

I will submit a pull request to resolve the exception by rounding out the invalid insignificant drop decimals which maxes out at 6.