I need quantity discount policy for my shopify -- 2

Hi, I am using Shopify Debut template. I need a code editor to create a quantity discount policy as follows: Upon multiple items purchase, our shopping cart will automatically deduct discount from total order. The system is calculating discounts according to the following criteria: Buy 3 items, get 5% off Buy 6 items, get 10% off Buy 15 items, get 15% off Buy 30 items, get 20% off Buy 50 items, get 40% off This should be done as follows: 1- On cart screen, the customer should see the amount of quantity discount (see example files). 2- On both checkout screens, the total should be seen after deducting the discount (see example files). Upon award, the freelancer should tell me what template files are needed to edit and I will send copies of these files to the freelancer. When project is done I will use the freelancer files and check the results. I just want to make sure that my original files are safe. Please ONLY Shopify experts should bid