Blender's coordinate precision

Hi all,

I want to use Blender to create 3D building models from 2D footprints that have a certain coordinate precision, which I want to retain. After finishing the model in Blender I want to export them again (e.g. as Collada) in such a way that the coordinates of the original match the 3D model exactly. In my case the coordinates (both x and y) have 6 positions before and up to 9 positions áfter the decimal point.
After some experiments (Blender newbie here!) I found out the decimal part get’s rounded: the thing I don’t want.

Can I overcome this issue somehow? Or stated differently, where can I find more documentation on this?

Thanks in advance,