- Go to Store -> Configuration -> Product Pricing Rules
- Click “Add a pricing rule”
- Give your rule a name
- Under “Actions” click “Add Action”
- Under “Commmerce Line Item” choose “Multiply the Unit Price by Some Amount”
- The data selector should be “line_item”
- The amount should be .9 (in other words, multiply the price by .9).
- Now all products have 10% taken off of them.