Enter the bill amount, pick a tip percentage, and split it among the number of people.
The bill amount is multiplied by the chosen percentage (10%, 15%, 20%...) to get the tip amount, which is then added to the original bill for the total.
Yes, alongside the ready presets there's a field where you can type any percentage manually.
The tool divides the total (including the tip) by the number of people you specify, and shows each person's share separately.