"Fixed Discount" is converted to "Percentage Discount"

Hello,

I need to enter a "Fixed / Flat Rate" discount
The option is there, but after the form submission it's converted to "Percentage" which sometimes lead to wrong discount amount due to rounding

Example:
Total price: 373.7$
Fixed discount: 269.10$
Total price after discount: 104.60$

After submission it will be like this:
Total price: 373.7$
Percentage Discount: 72% (fixed = 269.06)
Total price after discount: 104.64$

We have here 0.04$ difference, imaging this on many invoices


Thank you