The reason Blitzmax probably doesn't round floats when printing, is because if it did then you couldn't print the real float value.
Bingo.
BlitzMax's float->string conversion attempts to produce the most accurate representation of the underlying value as possible.
So it should now be possible to write a float to a file, as a string, and read back exactly the same value - an oft. requested feature of Plus/B3D etc.
I didn't really give this much thought pre Max, but I now feel strongly that this is the only sane approach for a 'built-in' float->string conversion to take.