It's actually the same number of asks: a tipping checkout asks for the donation, then the tip, and many also layer in their own upsell. A transparent checkout asks for the donation, an optional impact-based upsell, and an optional cover admin contribution. The difference is what each step communicates.
A "tip" implies the money rewards a service or goes to the cause, when it usually does neither. A cover admin ask names exactly what it's for: the real cost of processing the gift, typically a few percent. And tip percentages tend to run far higher than a transparent admin fee, often 15–20% versus around 5%, so it's the same friction, but very different effects on trust and on the dollar amount your organization actually keeps.