Welcome to the Community. Let me share some clarification about setting up products in QuickBooks Online.
Currently, an option to add multiple sales prices for each item is unavailable. There are two workarounds you can try to handle the three selling rates.
You can either set up additional inventory to separate sales rate or enable the price rule feature (available in Plus and Advanced version). It allows you to control the price of your products and services.
To turn on price rules:
Click the Gear icon in the upper-right corner and select Account and Settings.
Select the Sales tab.
In the Products and services section, select Edit ✏️.