Produce they provide portion bags and have been programed to give you an accurate weight on your items purchased. I would think u wouldnt want to pay for extra weight if you want to package prior to paying because there is no way to tare, or 0.0 the scale prior to purchase. I would say after purchace would be best for your own jar or package, just to give you the best possible price.
Idk about bringing in your own jar to fill an it brings up the question of what you want in it but you can pre order items to be prepared for you.
What are you trying to buy.
What kind of jars?
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