Mysql and rollbacks

I'm developing a site where I anticipate the need to make several updates to several forms, and I'll want to "commit" them all at once (i.e. if there's a failure with any of the transactions, I'd like to be able to back out to before I started). Is there a decent way to do this with PHP and Mysql? Obviously start with ignoring user interrupt, and I was thinking a fairly easy way to reduce the risk is to perform numerous tests before attempting any activity, but that means at least doubling my database activity - does that pose more performance issues than it solves? Or has someone else got a good strategy for dealing with this? Perhaps writing temp-rows, and then executing some sort of stored procedure to move all the temp-rows to the real tables in one fell swoop? Or, really, any wisdom to impart? -P