The professional "To be Continued"

SO first off, I'll admit this will probably sound like I'm just a bitter old man, who hates people. That's only partially right. I'll start off by saying that I am not a personable person, but I can manage a full conversation with a stranger. I have no problem chit chatting with someone when the situation deems it necessary to fill an awkward void. But, I shall say this, filling voids is something everyone should take a class on because I would say 70% of the people I run into on a daily basis, have no clue how to time their conversation.
Obviously there is a catalyst to why this is coming about. Case in point. Today while at the bank, I took my rightful place in front of the teller, and began my transaction. I am making a deposit, and getting some cash back. Something that in all should take no longer, than 45-60 seconds. I politely say "hi" and begin a polite "how ya been". Big mistake. Look,in my head I understand whats going on. To stand there and say nothing would seam psychotic. But to me, to stand there and tell this lady what I had for lunch, and what my plans were for the summer is nothing I want to get in to. Its the end of the day, its Friday, and I would have to think, no one wants to be there, at the bank near closing time.
So, back to chatty McBitch. She asks what I'm doing, I say depositing and getting some cash back. That takes about 5 seconds, so I got about 40-55 seconds left here. She begins typing in everything, la la la, asks for ID, down to about 25-40 seconds left. Hands me back my ID and then begins to ask me if I work for a construction company. Fuck. Obviously she has seen the check, which has the company logo on it, so I cant really say no, and stop the conversation cold. So now in my head, my time frame has been thrown way out of whack. So I answer the simple question, with a simple answer, "yes". Praying to the lord Jeeba above that this will halt further investigation. So at this point the whole transaction is about 95% complete and all I need is my money back.
Then it begins. An in depth explanation of how this ladies sister had some work done at her place, and the contractor something, something, something. I only say "something" because I honestly have just full on tuned her out. But at this point I realize that my transaction is complete. She has slipped my money and receipt back to me during her riveting story. So as she rambles on I contemplate how one could get out of this situation. On a TV show at this point "to be continued" would pop up on screen. The old Sienfeld joke that as you are about 2 minutes from the show ending, you know that cant finish the story,so you know the "To be continued" is gonna pop up. So why cant I use this in real life? Why cant, once I'm done, and the shows over, can't I say to this lady "Sorry ma'am, to be continued"? And just walk away? Why must I now endure 4-5 more minutes, of me standing at the window trying to fight back throwing a punch just to get out of there??? And lets understand here, theres more people waiting in line! So now it looks like I'm the jerk who's taking up every ones time.
As I said in the beginning, I understand polite conversation, but damn it, I knew at tops we had a minute of our day to fill, and this lady grabs a 10 minute sandwich of crap. So my only tip, is know your time frames people. I had a minute of how ya doin, nice weather, transaction done, in and out boom, done. If you know or think about what you are about to do, the people behind you are going to appreciate you so much more. And if you have to, just throw up the hand and say "sorry, to be continued". 3,2,1 terrible.