Hello,
This is all happening because, in the WooCommerce settings, there’s an option to round numbers to whole numbers — just like in your case: https://monosnap.com/file/h8gUdB0e9MiIcDOQeJTBA5YSdUNNox. In your situation, 5% of 70 is 66.5, and if you multiply that by 19, you get 1263.5 — which rounds up to 1264. This calculation is done by WooCommerce itself.
We replicated the exact same scenario with a default product (without Dynamic Discounts), applied a discount that results in a decimal: https://monosnap.com/file/9yOJdkJYAimKHq2AN0u5a7Jul3Qu0a — and as you can see, WooCommerce calculated it the same way: https://monosnap.com/file/GtWbFGfyhLOgeAlFllIXTn3tFbOFWU.
Kind Regards
.
