Like everyone said, it varies from county to county. In Ocean Co. 10-9 is arriving on scene, but in a few Atlantic Co. towns it means phone call. There are some standard ones across the board like 10-4, or 10-7 (out of service/off radio)
Click on this link for the Woodbridge Twp. Database. Middlesex County, New Jersey (NJ) Scanner Frequencies and Radio Frequency Reference
On the left side, near the top, click on Wiki.
When the page comes up you'll see a list of Woodbridge Township Police Codes and Fire Pager Tones.
At the bottom of that page click on "Edison Township. Includes Fire and Police Signal Codes"
Those are the only code/signal lists available for Middlesex County.