The Proposal:

Current :

• Discounts at Patient and Client level based on either % or $ value.
• Products have a maximum discount which defaults to 100%.
• At invoicing of a product the system applies relevant discounts and then checks it doesnt exceed the maximum discount and applies a discount as a $ value. 
• Discounts can be applied to the fixed price component or it can be excluded based on the discount type.
• Updating the qty or price will cause the discount to be relcalculated.

Suggested Changes:

• Add a new cost price discount - this would be selected during discount setup, and when applied would discount the product to sell it for Cost plus relevant tax. (probably relevant for staff)
• During product price creation the maximum discount will be a calculated value based on the calculated product markup, this will mean maximum discount will never allow a product to be sold below cost via discounting.  The discount can be overridden to reset it to 100 % at product creation OR overridden at product sale to sell below cost.
• Change to the Discount fields at product sale to allow for the entry of % based discounts. Upon entry the entry will accept an entry (for example 10%) but the system will take this figure calculate the discount and update the field with the calculated discount (like a macro).
• A warning box will pop up should the applied discount exceed maximum discount for a product.

Please make comments below if this specification would suite your needs and we can get Tim A to comment on applicability.