In the past it was used to increase the number of beds calculated via a percentage not taking into consideration availability (effect only with a percentage lower than 100%).
Example old: 30 beds available 10% and FloatMin 4 lead to 4 beds (instead of 3 without FloatMin)
Example new: 3 beds available 100% with FloatMin 4 leads to zero because the minimum of 4 isn't reached. (makes sense if beds are sold in chunks of 4 beds for private rooms)
Additionally the new FloatMin calculates only a multiple of FloatMin. The new behaviour is only applied for FloatMin values lower than 10. 10 and more keeps the old version.