No, it wouldn't, just ask them to offer lower donation amounts/tiers, if the existing tiers are too high.
This really would not be much harder than managing an RSS feed.
If an adequate amount of money goes to doing the math to divide what would be donations equally, after Google's cut of course... then you are being lazy, and are fine with giving Google money.
Would you give to a charity that had the same 'admin overhead' to 'actual money put to use' ratio as Google takes in their cut?