Wrong output for precision=2

[pedroluisneves]

Hi,

I notice that using precision=2 does not gives the expected result:

EngNumber(10e-6,precision=1)
=> 10.0u

EngNumber(10e-6,precision=2)
=> 10u

EngNumber(10e-6,precision=3)
=> 10.000u

EngNumber(10.1e-6,precision=2)
=> 10.10u

Thank you for the great work,
Pedro