Congress's rhymes with:
congresses, congresses, congresses, congress', congresses, actress's, actresses, choruses, congress', congresses, cypress's, embarrasses, fortresses, gavras's, heiresses, irises, mattress's, norris's, retroviruses, sampras's, virus's, waitresses, walruses
Congress's sounds like:
cancer's, cancerous, cancers, cankers, ceniceros, censors, changers, commissaries, commissars, conagra's, concierge, concourse, concourses, concurs, congress, congress', congresses, conjures, connoisseurs, conqueror's, conquerors, conquers