Sterilize jars and lids in boiling water for at least 10 minutes. Let simmer while making jam.
In a large saucepan, combine strawberries, cranberries, pectin, and margarine. Bring to a boil. Stir in sugar, and return to a boil. Cook for 1 minute; remove from heat.
Quickly fill jars to within 1/2 inch from top. Wipe rims clean, and put on lids. Process in a boiling water bath for 5 minutes.
