[I have to pay a service fee to TIP a SELLER?!?]

I just found this out myself. I do understand the logic behind it with people trying to avoid fees but i think they should have gone about it a whole different way. eBay did the same thing by taking fees on postage.
I told the seller if she could do a certain task i would tip her as the work was a little difficult. Then when i went to tip. I wanted to tip X amount and the total was 1.5X. Thats outrageous! Now i’m unsure what to do. If i had her personal paypal i’d send it direct.
This is the second time i’ve used fiverr and it’s left a sour taste.