CS5 won't run Camera Raw 7 onwards. So you can't run a suitable Camera Raw update on CS5.
As you need at least 8.2, your best free option is to download DNG Converter 8.6 (or 8.3 if you're on an older incompatible OS).
Camera Raw 6.7 is the recommended latest version for CS5. Set DNG Converter's Compatibility preference to 6.6 onwards.
DNG Converter processes folders of raw files and creates DNG versions, which will open just fine in CS5.
If this is all too much trouble, your other options are to use Lightroom or upgrade to CS6/CC. But these cost money.