up_to — the tier's upper limit (in terms of the SKU's quantity).price_amount_cents — the unit price to be used for the related SKU if the total quantity of the associated line item is lower than (or equal to) the up_to limit.up_to attribute is null the related tier will be considered a beyond tier, meaning that the specified unit price will be used if the SKU's quantity is greater than the maximum tier's upper limit. If no beyond tier is set the standard SKU's price amount_cents will be used as the beyond price.