Taxes are divided in proportion for each recipient or payment method. For example, let's say the order total sum is $100 and 10% is a tax, which amounts to $10.
Let's assume that 3 people participate in payment and prices between them are distributed as follows: $10, $40, and $50.
In this case, taxes for each of them will be 10% of the sum of their share from the order amount – i.е., $10 * 0.1 = $1, $40 * 0.1 = $4, and $50 * 0.1 = $5, respectively. In total, it will be $1 + $4 + $5 = $10, which corresponds to the taxes on the total cost of the order.