Priceline taxes & fees vary?

[ericball]

I used Priceline for the first time to book a car rental (MIA fullsize 11/19/09-11/23/19).

10/03 lowball $16/day taxes & fees $51.29 total $115.29

10/04 $19/day taxes & fees $47.76 total $123.76 the taxes & fees went down!

10/05 $24/day taxes & fees $56.46 total $152.46

10/06 $26/day taxes & fees $55.94 total $159.94, but it rejected as I was less than 24 hours

10/06 $26/day taxes & fees $58.78 total $162.78 - accepted, but the taxes & fees changed from the earlier attempt!

Okay, this is whacked out. Now, I can understand that the taxes (being a percentage of the price) will go up as I increase the bid. But then why did it go down that one bid and then change for the same bid on the same day? Is there a penalty being worked into the price so the more I bid the higher the fees go?

I don't begrudge Priceline making some money off the deal - the fees give them a minimum amount they will make when the bid & ask are close. (I also appreciate that they cover all of the taxes and rental co's fees which they may not know 100%.) But you'd think it would be a fixed amount or percentage. This sniffs of them playing the system in their favour. (i.e. hike the fees if the spread is too small).

I also would have preferred to be able to bid a flat dollar amount rather than a price per day which then gets taxes & fees tacked on. I appreciate it looks better on a comparison chart, but it's made worse because the variance in taxes & fees.