Well - I personally try to avoid nesting my transactions (since ultimately only the outer one "counts"), but that being said - if I'm worried about scoping and knowing what's being committed, then I start "going manual". Meaning - start naming my transactions and carry a variable in my stored procs telling me how many transactions I started with.

If it gets too messy - then I tend to revert to relying on other methods to allow me "transactional integrity. Such as using a customized "roll your own" scenario for the simpler inner transactions.