Bob is spot on. Many of those measurements in SpoCalc don't translate to an appreciable difference in the Spoke Length it spits out. Get the main stuff right and you will be close enough.

I stressed out about this kind of stuff really hard when I was ordering spokes for my first wheel build and the most important thing is just what Bob says, get the main things right. ERD, flange diameter, cross number and wL, wR values are the most important things. If you play around with the other values in SpoCalc you'll notice that changing them doesn't translate to more than a couple tenths of a millimeter.

If spocalc is saying 292.8 and 292.5, I'd go with 292.

I've ordered the wrong length spokes before...it was obvious before I ever started tensioning the wheel and ebikestop.com took them back and exchanged them for the proper length. All I lost was a couple bux in shipping and a few days.

If you are super stressed out, just post the numbers you are feeding Spocalc and any of us can run them through ourselves and check your work.