Right on!
When we used phrases like, “since x and Y”, “over the x # of years”, or “for Y duration of time”, you are implying that the action is up to the present. i.e. Mary and Jane have been friends for the past 5 years. I have worked for IBM all my life.
If the action (work) terminated, I would simply say, “I worked for IBM before” or “I had worked for IBM for 5 years ” (before changing job to anothe rcompany).