You can either follow along this video tutorial or read below.
An unavoidable part of ecommerce business is payment gateway Transaction fees. The rate between Paypal, Stripe and other gateways can be different. Shopify also charge an additional fee for using external gateways other than Shopify Payments. This is between 0.5% – 2% depending on your Shopify plan.
You can input these rates in TrueProfit. Go to Transaction fees, then write the rates for each gateway you use.
For example, a typical store using Stripe would pay 2.9% + 30 cents + 1% Shopify external gateway fee, assuming it's using standard Shopify plan.