Do they unlock something? I read the wiki and they say they can't be built anymore.

Originally posted by GunsForBucks:

Maybe I should play the lottery?

The other day I paid 7.77€ on register number 7. Didn't plan any of it, I realized it when they told me. Went to buy a lottery ticket for the giggles and didn't earn anything and was assaulted by a leashless dog on my way home.
I'd say don't do it, stay safe until life forgets about balancing your luck out.