You can set role based pricing in a couple of different ways.
Setting global role based pricing rules
To set global pricing rules, go to WooCommerce > Settings > Fees and Discounts and ensure the ‘Enable User Role Pricing’ option is selected.
You can then click on the ‘User Role Pricing’ menu item and set rules for each user role.
In the ‘Adjustment’ column, pick the type of discount or fee you want to apply.
In the ‘Amount’ column, pick the amount.
Setting role based pricing by product
If you want to apply role based pricing on a product by product basis, you can do so from the edit screen for individual products.
Click the ‘User Roles’ tab in the ‘Product Data’ section and enter the adjustment type and amount as above.
You can also follow this tutorial on setting prices by user role in WooCommerce.