The accepted answer is fine. There is an official help on options available.
Also basic Shell commands will do nicely here:
for x in 10 100 200 ; do inkscape --export-png logo${x}.png -w ${x} logo.svg ; done
On the command line in windows use this line from @avalancha in the comments
for %x in (100 200 300) ; do inkscape --export-png logo%x.png -w %x logo.svg ; done