Promo code discounts and cashback credit are delivered in Bonus Coins. This means, for example, that the total to pay will not be discounted by 20%, however you'll be able to choose bonus items (freebies, in addition to your main products) up to 20% from your shopping cart.
1 Bonus Coins = $1
In the purpose to avoid extra shipping costs, customers can choose freebies (products acquired with bonus coins) only from the same warehouse as the products from your main order. So if you add to cart products from Warehouse 1, you will be able to choose freebies only from from Warehouse 1. If you choose products from Warehouse 3 & Warehouse 4, you will be able to choose freebies only from Warehouse 3 and/or Warehouse 4.
Also, if you do not select freebies for the maximum amount available in your wallet, unused bonus coins from the promo codes and bitcoin discount are credited back into your account. Moreover, you receive an additional Cashback in Bonus Coins as well, from 5% to 15% when your total orders value reach cumulative sums of $1K, $2K and respectively $3K. You can use them later, on your future orders.