Progress Invoices based on percentages rounding Discount items to nearest whole percent number

I've been working with a client to fix some issues on the invoicing/payment side of their QuickBooks Desktop Pro installation. We're using Estimates for a customer's quote, then generating Progress Invoices for payment amounts (e.g. first a $750 line-item retainer payment, a 50% payment due ~60 days prior to the final payment, and the final payment). Most of the time, the company's customers adhere to this 3-part payment system. However, some of this company's customers pay numerous times with non-rounded percentage payments (e.g. on a $12,985.26 estimate total, the customer pays $850, which is 6.55598% of the estimate total). We enter in the calculation to the furthest decimal place and create the invoice.

Unfortunately, every time we've created an invoice with one of these non-whole number percentage (from the Estimate, "Create invoice" > "Create invoice for a percentage of the entire estimate"), QuickBooks rounds only Discount items to the nearest whole number—in the above example, the discount item turns to 7.00%. The other percentages do apply evenly across any of our regular, non-discount items (with slight variations in the 100ths place due to rounding differences). We can usually fix this issue by manually overwriting the discount items, but it is time consuming and irksome when generating an invoice for every payment. Is there a setting that we don't have turned on affecting the rounding of only the Discount items, or some other issue at hand?