Tvilas keilim on products for sale

I own a small specialty kosher food business. 100% of our products are sold to our Jewish costumers.

We have a line of cakes that are baked and sold in glass mason jars. You eat the cake from the mason jars.

Am I required to tovel these glass jars since I am putting food in them or is the requirement on the customer if and when they want to reuse the jar?

Tevilah is required.