Exact discount distribution for multiple products in the order

[Val9]

I need to know how exactly Shopify distributes a discount among multiple products in the order.

Your help page https://help.shopify.com/en/manual/discounts/discount-types/percentage-fixed-amount states:

"If your discount is set to discount all products, then the discount is applied proportionally across all items in the cart. For example, if you have a $50 discount applied to a cart with a $50 and a $100 item, then the first item is discounted by $16.50 and the second one by $33.50"

This is NOT proportionally. Proportionally would be $16.67 and $33.33, for example (1/3 and 2/3).

How is Shopify "rounding" proportions to  $16.50 and $33.50?