A serial number is not a tracking device. A sufficiently determined adversary with unlimited resources and access could maybe track you via it But practically

A serial number is not a tracking device. A sufficiently determined adversary with unlimited resources and access could maybe track you via it But practically speaking an afternoon of shopping, exchanging coins for banknotes, breaking those into coins and back again will make it as untraceable as possible. Especially since we're talking about 60 euro per year