After doing some research it sounds like the easiest way to save PDF files on an iPad is to save the document to iBooks. If you have the iBooks app downloaded from the app store and the document open and ready to print, tap on the screen and you'll see a black bar appear at the top of the document with a button in the right corner saying "Open in iBooks". Click that button and you should see your document open in iBooks as a PDF. I found a quick video on this process.

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