One-upsmanship, Nippon-style

Buying lunch at Satey today:
Me: arigatoo.
cashier: arigatoogozaimashita.

After geting my ass kicked by Shuichi at 9-ball today:
Me: Hey, thanks for the game.
Shuichi: Thank you very much.

Hmm. After grocery shopping at Marugo today:
Me: arigatoogozaimashita.
cashier: arigatoogozaimashita doomo.

I refuse to let these Japanese out-thank me! Buying beer at the Noguchi convenient store:
Me: Doomo arigatoogozaimashita (with a bow).
cashier: (after picking up and accidentally dropping the 6-pack on the counter)
Arigatoogozaimashita, doomo sumimazen onegaishimashita.
(with a deeper, longer-lasting bow).

I suppose it's too much to ask at this point of my learning Japanese to out-thank or out-apologize these Japanese at their own game.