You're probably thinking, "Wait a minute. IBM was American! The closest America ever got to the Nazis was when Indiana Jones wore that uniform as a disguise in Raiders of the Lost Ark!"
Back in those days, the only way to keep track of huge databases was with an extremely complicated system involving punch cards, and IBM was the best at constructing and maintaining those databases. IBM's punch card databases could keep track of anything: financial ledgers, medical records... Jews. According to a book a guy wrote about it, as soon as the Nazis invaded a country, they would overhaul the census system using IBM punch cards. Then they'd track down every Jew, Gypsy and any other non-Aryan until they were all rounded up onto cattle carts. And the next stop wasn't Space Mountain.
[The DB] tracked people based on their religion, their location and even how they'd be executed. For instance, Prisoner Code 8 was Jew, Code 11 was Gypsy. Camp Code 001 was Auschwitz; Code 002 was Buchenwald. Status Code 5 was execution by order, and Code 6 was gas chamber. Holy shit, people. Seriously, IBM. What the fuck?