Tiebreak according to IIHF website:
--2 teams: H2H
--3 (or more teams): Points against other tied teams, goal differential, goals scored. There are more, but it won't get past the first criteria
US plays Finland, Germany plays Denmark (Denmark is already through to the qualifying round)
US win in regulation + Germany win in regulation or OT: Finland to relegation round
US win in regulation + Denmark win in regulation or OT: Germany to relegation round
US win in OT + Germany win in regulation: Finland to relegation round
US win in OT + Germany win in OT: Germany to relegation round (Finland has 4 points against tied teams, USA 3, Germany 2)
US win in OT + Denmark win in regulation or OT: Germany to relegation round.
US loss in OT + Germany win in OT or regulation: USA to relegation round
US loss in OT + Denmark win in OT: USA to relegation round
US loss in OT + Denmark win in regulation: Germany to relegation round
US loss in regulation: US to relegation round (regardless of Germany/Denmark result)
So it's quite simple for the US: if they win (regulation or OT), they advance. If they lose, they go home except if they lose in OT and Germany loses in regulation.