I used to cut to the 5 leaf. However, now I snap it with my hand just under the bud. But I'm not letting most of my flowers bloom, in hopes of a stronger root system :(

Some roses will resent it if you just whack them off and will sulk a while before starting to regrow. Others don't care much and will continue blooming happily a long. But if they're really over grown that much I'd say just go for it and take them down to where ever you need them to be. If you're going to do that though in your zone you need to do that now! You don't want to be cutting them way back just before winter sets in. If you do it now they should still have time to give you a fall flush.

On large, bushy plants with many spent blooms, I use a hedge clipper to deadhead and don't worry about where the cut falls. I have been doing this for many years with no problems.

On other roses, if they are too small, I just snap off the blooms. If they are too tall, I take 1-3' of stem and cut just above a leaf. As Seil says, do that deep deadheading in summer rather than near the end of the growing season.