Do i need to register with any s.o.s. to conduct online business?

ok, i now understand that an llc can be formed in any state, but that it also needs to register itself seperately within any state that it will be doing business/operating. So lets say i file and form the llc in delaware, .. great ... now do i even need to register with my home state since all transacting is being done online? or do things such as having a bank account qualify as "doing business in" a state?