This can be done with our discount feature. You can create automatically applying discounts that kick in after certain quantities are ordered. To do this go to Seller Admin > Add/Edit E-junkie Cart Discounts.
Start by selecting one of the products you would like to discount in the Product menu (you can also select All Cart Items if you wish).
Then give your discount a distinct Discount Name. This is for internal tracking so do not ever use the same name twice or you will just overwrite your existing discounts. If you want to make a series of discounts that kick in for higher quantities that is fine, you may want to name those something like "Quantity Discount 1" then "Quantity Discount 2" and so on.
Leave the Discount Codes field blank. This means the discount automatically applies when the other conditions are met.
Set Min Item Quantity to the minimum order amount before the discount kicks in. You'll notice there is no Max Item Quantity but there does not need to be. If you want to make a higher discount for higher quantities just do so and set it to have a higher minimum. Our system will select the most appropriate discount on based on the size of the order.
You do not need to set expiration dates or max use or any of the other conditions.
For the discount, bear in mind that product discounts are locked at flat amounts. If you wanted to give 10% off the price of an item you can do so, but you will need to type in the flat amount based on the product price rather than the percentage. All Cart Items discounts can have percentages.
Once you have created such a discount you should see it listed in your cart and sales logs as a "Current Promotion" when the conditions are met.
As a final note, be sure that you are using our recommended Add to Cart buttons for this, since the other options don't support our discount features.