Error (or bug) on OpenBSD web page

[Kruse_(_at_)_email_(_dot_)_si]

Hi,

On OBSD https://https.openbsd.org/cgi-bin/order is stated:
Orders of 12 Shirts or more receive a 20% discount

When I tried to order T-shirts I got:
Your order currently is: 
-> 20 Secret Service Shirt (L) @ USD $20.00
-> Total: USD $400 + Shipping. 
-> 20% DISCOUNT on 12 or more shirts (20) : USD -$20 
-> Final Total: USD $380 + Shipping. Shipping is FOB our depot.

Maybe I'm a little weak in mathematics :) or is this just a 5% discount?
I would also like to ask what FOB stands for?

Thanks and regards,
Kruse

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