Bellett-metrics

[JT191]

I'm taking measurements and trying to get them as accurate as possible. A lot of this has to do with making sure the thing I am measuring isn't bent or decayed and taking into consideration for manufacturing variances.

If it was an American car, I would be looking for numbers that were even inch or 1/8 inch increments, because sane people will design things that have dimensions that do not have ten or twelve places to the right of the decimal point.

Has anyone noticed if Belletts seem to be made with dimensions rounded to the even millimeter or increments of five or ten millimeters?
I have a couple measurements that are very, very close to even numbers like 170 mm and 240 mm. I am trying to figure out if this is the standard and that I should correct all the rest of my measurements to even millimeter tens and fives, or if these are aberrations.

Any ideas or thoughts?