I'm American. So. A can is what holds things. A tin is a can that is being discussed by an Aussie/Brit. Also, Mysterious Sue, if you were wondering, in the States, no, they are "canned goods." "Tinned goods" is a phrase I've never heard before.
Anywayyyy, so you should probably say tin. Because we seem to like people who don't talk so good.
*Izzit. Sorry, forgot to put that there so you could understand me.
Not that it matters. Eventually you'll be skeduling your lunch breaks during which you will heat up soup from a can. We're just that nefarious.