While there isn't currently a discount field for services in Practice Ignition, there is a work around which should allow you to offer discounted rates to your clients.
You can apply a discount to a service by directly changing the price of a service when drafting a proposal:
In the example above, you could override the default price and reduce it to say $350, effectively applying a discount of $50 or 12.5%. The drawback of discounting this way is that the client will not see that a discount has been applied when viewing their invoices.
In order to show the client that they are getting a discount, you can simply add the details (standard price, discount rate, and discounted/final price) to the 'Service Description' while setting up the services on the proposal.
Please let us know if you have any questions about applying discounts in Practice Ignition, you can email your questions to: [email protected]