It's a good idea to keep the edges in the same dtype as the input data, it will make for fewer surprises, but I'm not sure that it's necessarily any more "correct". A value within an eps of a bin could arbitrarily end up on either side -- that's simply the nature of floating point.

 

Using decimals rather than sig-figs is a problem regardless of precision, and isn't that the same problem with C libmath round() ?

-CHB