Linked Server Between SQL Server and iSeries is rounding decimals
Figured it out!!

Apparently we didn't have the latest service pack installed. We had to install the 64bit version of the service pack (32bit version failed to install), and when it finished the decimal numbers were coming across.

EDIT: In case anyone was wondering:
We're using "IBM iAccess for Windows 7.1 (07.01.0800) (64bit)" and using "Microsoft OLE DB Provider for ODBC Drivers" as the linked server sql driver.

EDIT 2017: Seeing as I just ran into this problem again and had to hunt down the service pack again, here is the link to the service pack download page, so that in a few years when I run into this problem again I will find it easier...

http://www-03.ibm.com/systems/power/software/i/access/windows_sp.html