IF you just want to transfer the data into brand new files, you can export the data into tab, csv or merge files then import the data into FileMaker 12.
If, on the other hand, you want to convert the 5.5 files into the needed .fmp12 format, that can also be done.
First download a 30 day free trial copy of FileMaker 11: http://info.filemaker.com/Us_en_FileMaker_Pro_11_Trial.html
Use this version of FileMaker to open and convert your 5.5 files to the .fp7 format used by versions 7 through 11.
Then launch FileMaker 12 and open the converted .fp7 copies from the File menu to get copies converted into the .fmp12 format.
Be prepared to invest some time into making some changes to your converted files before they become fully functional in FileMaker 12.
Here are some additional links about the conversion process that you may find helpful:
Converting to .fp7 format: http://help.filemaker.com/app/answers/detail/a_id/750/kw/converting
Converting to .fmp12 format: http://help.filemaker.com/app/answers/detail/a_id/10571/kw/converting
Feel free to post back here with any issues you encounter that don't seem to have been covered by the KB articles.
Yes, I found the 5.5 to 11 (trial) to 12 "bridge" and started ot post that, but lost it before hitting Post Answer. I wish that there had been a "big" note in the v12 CD case saying to do that.