Inside Anatella, there is no rounding anywhere (unless you use the "round()" function of the calculator, but that's normal). Especially if you use .gel_anatella files to save your data, you are guaranteed that everything is perfect, without any rounding.
On the other hand, when you export to a format external to Anatella, then there can be a loss of precision due to rounding.
In your email, you show a screenshot of Excel. By default, the output to an excel file is done without any rounding: This is visible through the parameter here:
This parameter is documented in section 184.108.40.206. of the "AnatellaQuickUserGuide.pdf" (press F1 inside Anatella to read this PDF).
Also, by default, there is a little rounding when outputting to a text file (.csv or .txt) (because, otherwise, these files can get very large very quickly). You can see it here:
If you don't want any rounding in the .txt output, just choose %.16g (instead of %g) in this option.
Also since Anatella 2.76, the option to display in the "data preview" window all the columns with the "Float" meta-type with the maximum precision visible on the screen, I available. You have to choose the "%.16g" option here:
This way you can see that all calculations are done at maximum precision everywhere in Anatella (but it is generally less pleasant to read).