The best answer is to bring your own bag from home. Plastic sacks may not contain post-consumer plastic and are not manufactured in Oregon. Many grocery stores have plastic bag recycling programs. Bring a sack from home for your produce, bulk, and carry out needs. Look for packaging that is reusable or refillable.
Some items have packaging that has been minimized in size.
Concentrates and bulk items are excellent examples of source reduction. Evaluate the packaging of the item. As a customer, you have enormous power. Fill out customer satisfaction cards, write to your grocer, or directly to the product manufacturer. Let them know that you want to see them support sustainable packaging design.