This is the step from the zero of that item, so should be a factor of the maximum, e.g. 2, 3, 4, 6 or 12 for the hours. I can't see a neat way to do it every 10 minutes replacing 5,15,25,35,45,55 , although you could build it something like this:-
The best place to check if your host supports it is the manual page for the file crontab.
Often this can be found with man 5 crontab but check with man -k crontab to get the various options for pages you can read, such as Unix.com man page for crontab file
Don't forget, you should be using the 'crontab' command to enter cron jobs. If you're editing the crontab file directly yourself then cron may not know about the changes for up to 24 hours and therefore the job(s) won't run. Otherwise restart the cron daemon from the command line to alert it of the changes.
I've found this document that suggests that it has an extension to allow this:-
5/10 * * * * /you/command/here
.... but there is no clue which variant this might be deployed in. It is rejected for me on CentOS 6 with this:-
crontab: installing new crontab
"/tmp/crontab.cVRcNc":3: bad minute
errors in crontab file, can't install.
Do you want to retry the same edit?
It might be useful, but I'd prefer a fully functional external scheduler that allows for structured job planning and dependencies unless it's simple jobs running on many and widely distributed servers. Horses for courses I suppose.