When the outer transaction is rolled back does not it roll back all modifications, irrespective of any commits by the inner transactions? It makes no difference whether you have transactions in the procedure. (as shown below)

create table logger (logentry varchar (30))

go

create proc Testproc @entry varchar(30) as

begin tran

insert into logger values (@entry)

commit tran

go

begin tran

insert into logger values ('Outer')

exec Testproc 'Inner'

select * from logger

Output

======

logentry                      

------------------------------

Outer

Inner

(2 row(s) affected)

rollback tran

select * from logger

logentry                      

------------------------------

(0 row(s) affected)