Go through the following steps to create Buy X for $ offer. 

Step 1: Install App

Install Discount Box app -> Open Admin panel -> Click on "Apps" tab -> you will see Discount Box app listed as shown in Image.

Click on this listed Discount Box app.

Step 2: Go inside Discount Box app

# When you go inside the app, you will see 3 tabs on top which are Dashboard, Setting & Create Offer.

# Click on Create offer button from top 3 options, you will see options like below image.

# Now click on Create Offer button of Buy X for $.

What is Buy X for $ offer?

When a customer buys many products from the same collection then give a discount on each product. You can apply a discount with a fixed price/percentage.

Give discount in two different ways.

1. Buy any min X Qty from the following and get " Y % off on each item". 

Example: Buy any 5 from fashion collection and avail 10% off on each item.

2. Buy any min X Qty from the following and get " $Y off on each item".

Example: $10.00 off on 2 footwear and a pair of socks.

Note: Make sure that your offer amount is less than product original price. 

Step 3: Create Offer 

-> To create offer select Buy X for $ offer Type from DropDown box.  

-> Select specific products else entire collection.

-> Add percentage number else dollar amount in given textbox as shown in below image.

Step 4: Advance Settings  

-> There is also an settings of Offer message texts. These messages will display when product added to cart & offer applied successfully. 

-> Do additional configuration to customize your offer. You can set a start date & end date of the offer. All these options are optional.  

-> Do not forget to click on SAVE button to save all the settings.

In your store, this offer will display like below image.