Shipping can be estimated using formulas you enter. These formulas can factor in number of items, weight, and price and can have multiple tiers.

For shipping established by formulas you enter, configure the product catalog block used for checkout  and select "Set by Formulas You Enter" as the Shipment Charge Calculation.

The "Handling charge per order" is ignored. If you want a charge per order, enter it into the formulas.

This charge will appear as "Shipping" in the cart's subtotals.

Once you have saved a product catalog with this setting, re-enter its configuration screen and there will be a Shipping Calculations link at the top.

Free shipping is also an option in promotions. When a promotion establishes free shipping the shipping price will be lowered by the amount of the lowest default formula. If this brings the cost to 0 or less the shipping charge will fall to $0 and there will be no shipping line in the cart's subtotal.

Note: FreeShipping is not always the best deal.  A buy 2 get 1 free but pay shipping, for example, will typically be a lower price than just free shipping, so if you still see a shipping charge use Explain Promos to see another promotion with a lower price was used.

TBD:

Formula review and testing