Confirmed, Locked bootloader WITH root access! No wiping, no issues, just pure stock Nexus 10 with root access! And too think everyone is saying that the patched exploit since 4.2.1 prevents this & forces >fastboot oem unlock - Not the case folks! On both a WalMart & a Play Store Nexus 10, I have rooted without unlocking & WITHOUT wiping.
FOr those having issues, the USB driver has thrown a few loops.
I find the best way is to manually delete your Android device from Windows Device Manager, then delete the drivers manually via USBDeview & then install the Nexus 4 USB driver or the Naked USB Driver. You have to install it to both the device & to the fastboot device, which means once while in the OS & once while in bootloader. To activate USB debugging for this, you need to go into setting/about device & tap "Android Version" 7 times. That will force show Developer options in the settings menu, where you can select "enable USB debugging".
One you have USB debuggin running & the new drivers installed, just click on Pauly's superboot-windows batch file or call it via cmd windows. Voila...You are unlocked & saved yourself an hour of re-installing apk's or waiting for new back ups via adb.