There is a product called "Seal All" it is specifically for that purpose.
I have used it in the past, work's awesome and its permanent.
If you take the time to read hisStep 1 : put some silicone on the hole .
Step 2 : Fill the Jerry can with a mixture of half piss and half gas add a pinch of kerosene for good measure
Step 3: put Jerry can conspicuously on your driveway or back of truck so some ****wit steals it
Step 4 : laugh to yourself as some thief if having grief with his newfound "gasoline "
Step 5: realize your a tightwad and go buy a new jerry can