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I'm sorry but I think you're out of luck. Camera Raw for Photoshop CS5 is limited to the 6.x series of Camera Raw. Newer Camera Raw releases (7.x, 8.x) only works with Photoshop CS6 as far as I know. Perhaps there will be an update to Camera Raw 6 but I wouldn't hold my breath. The last update was 6.7, for EOS 5D Mark III (and other cameras released around the same time).
I used Lightroom 5 for most of my image editing, but I also own Photoshop CS5. Lightroom is updated with the same functionality as found in Camera Raw for a lot less money than the upgrade to CS6 would cost me.
There is also the option of downloading the latest version of Adobe DNG Converter (free), which would enable you to convert your RAW images to DNG's which you could then open in Photoshop CS5. The RAW conversion in Camera Raw 7.x and Lightroom is a lot better than the old Camera Raw versions though, so you may lose some quality there.