I have a guitar with a floating bridge (Ibanez RG something) and I had no trouble with the tunings because I mainly used standard tuning or drop D.
But now I want to learn a song with a Standard D tuning (down 1 step) and every time I tune a string down the others get higher pitch and the bridge drops.

Is there any technique to tuning a floating bridge guitar to other tunings?
Tune down the strings, and just keep tuning till it starts to stay in tune, takes a while, but that's the best way to do it. If you want to keep the bridge floating, then your going to have to mess with the spring tension in the back of the guitar, it takes a while to set up, but that's life.
Read the FR sticky at the top of this forum.

Also, for the future, be aware of what you're buying before you buy something.
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