alucky, -You can float an idea or a plan, that is, present it to the public for acceptance--in the sense that you put a boat on the water and wait to see if it floats. -You can float stocks, bonds, or securities on the market, that is put them up for sale in order to raise money for an enterprise. -You can float a loan, that is, you can negotiate the terms of the loan. ‘Float a bill’ is related to floating a loan. The bill is the amount of money you would owe if you went on the vacation. If you can’t float the bill it means that you can’t arrange any way to finance the vacation trip.

Oh, there are so many idioms in every new language! But every idiom brightens language.

It is a joke. Floating a dollar bill (a dollar note) is a magic trick, where the dollar bill appears to float from your hand. The dollar bill, the bill at a restaurant, well, two different kinds of bills, but there is the joke man.

never heard of this expression, although I would guess the same meaning that you suggested.