Zend certified PHP/Magento developer

How to make compressed rar or zip files of certain size in Linux command line?

On my Ubuntu machine, I’d like to create compressed archive files of 10mb size for Windows users. So that a 25MB myfile becomes something like:

myfile1.rar
myfile2.rar
myfile1.rar

I could not find any working example of that in rar tutorials on Linux like here. And for zip, a command that I found

zip  -s 10m -r  myfile.zip  myfile 

Create files that can not be unzipped (at least not on the same Ubuntu machine GUI)

So appreciate your help.