Does Chargebee Checkout respect volume pricing, or does that only work subscriptions created using the API?
Chargebee supports volume pricing using a combination of API and different plans. The checkout page can be used for the initial signup by making sure that the customer selects the correct plan which corresponds to the volume which they are on.
Plan Volume: Price/unit
Enterprise (01 to 10) $10.00
Enterprise (11 to 20) $8.00
Enterprise (21 to 30) $6.50
Enterprise (31 to 40) $6.00
Enterprise (41 to ~) $5.50
This will involve creating 5 plans for each tier. When a customer selects a quantity which falls within a given range on your website, you can call the appropriate checkout page(which is plan specific) for this purpose.
The downside is that when the customer decides to change the quantity and this falls in a different pricing bracket, it has to be done via API.
Here is the documentation highlighting the same: https://www.chargebee.com/usecase-guides/volume-pricing/#setup