Under the floor or pillow?

Right now we are waiting for one of my daughter's top teeth to fall out. It is driving me crazy watching her play with it each day and I am hoping that it will fall out as soon as possible. However when it falls out we will be faced by a slight dillema - do we follow the New Zealand tradition of putting it under the pillow to be collected by the tooth fairy, or do we follow the Japanese tradition of throwing it under the floor? Japanese tradition is that if it is a lower baby tooth that falls out you throw it up onto the roof; and if it is an upper tooth you throw it underneath the en-no-shita which is the lower portion below the floor of a Japanese house. This is done so that the upper tooth grows healthy downwards, while the lower tooth upwards. I wonder what people do who live in really tall apartment blocks!
Unfortunately my daughter seems to be stuck on the New Zealand tradition of putting it under the pillow for the tooth fairy to collect. I wonder if it has anything to do with the fact that the tooth fairy replaces the tooth with money.....