I'm Andrew and I'm a community manager for Trulia, and so can speak on Trulia's behalf.
I've been looking into your issue, and replicating it myself. I think it's fair to say that you've found a bug on our site as our search tool is not behaving the way you'd expect it to. I have taken this issue to our engineers and they are working on a fix.
However, in the mean time I still wanted to find a way to help you with finding homes within 5 miles of 46057. Using Google Maps, I figured out what a 5 mile radius would look like from the center of 46057, and recreated on Trulia using our custom polygon tool. It's not a perfect circle, but it's close.
The end result is that I've found 5 homes within 5 miles of 46057, sorted by price from lowest to highest. Here's the link: http://bit.ly/GSs3Jf
I hope this helps. If you any follow up questions or comments, you can add a comment by clicking "Comment" below (in blue) or email me directly at firstname.lastname@example.org
Thanks again for reporting the bug. Now we can fix this and make Trulia better for everyone.