Here's what rhymes with customary.
marry merry nary very vary fairy bury dairy ferry wary cherry hairy berry sherry tarry ternary canary parry unwary harry tare barre terry faerie wherry ordinary capillary dietary stationary urinary prairie visionary honorary mercenary sedentary seminary veterinary scary stationery cautionary centenary remarry buffoonery legionary pessary actuary apiary cassowary humeri nondairy uncustomary secondary temporary arbitrary missionary pulmonary commentary coronary dictionary hereditary imaginary solitary adversary cemetery legendary ancillary budgetary dysentery estuary commissary emissary funerary itinerary papillary statuary luminary aviary bacillary concessionary equerry lapidary bilberry elderberry topiary plagiary sectary necessary military literary contemporary secretary monetary disciplinary momentary pituitary reactionary sanitary unitary corollary planetary salutary apothecary culinary fiduciary functionary mortuary obituary sanguinary savagery confectionery dignitary epistolary supernumerary unsanitary beriberi breviary diversionary dromedary huckleberry recessionary tercentenary chokecherry preliminary unnecessary evolutionary monastery sanctuary subsidiary vocabulary fragmentary involuntary judiciary maxillary pecuniary tributary inflationary deflationary expansionary probationary tutelary constabulary insanitary geostationary voluptuary bicentenary nonliterary extraordinary revolutionary beneficiary proprietary discretionary exclusionary expeditionary genitourinary paramilitary nonmilitary elocutionary nonhereditary cardiopulmonary interplanetary undersecretary eleemosynary noninflationary interdisciplinary multidisciplinary counterrevolutionary Words that almost rhyme with customary
belly allele jelly smelly deli telly underbelly vermicelli many messy heavy ready fairly rarely barely semi petty levy penny antennae heady levee medley spaghetti unfairly jetty teddy bevy faery jenny kepi leggy recce sedgy veggie healthy steady wealthy deadly lengthy gentry unhealthy fleshy carefree sentry sexy sketchy sweaty unsteady vestry belfry deathly gayety hefty machete confetti pebbly tempi testy breathy dressy pesky thready lefty wetly already directly especially twenty assembly scarcely elementary gently plenty complementary epilepsy freshly immensely densely frenzy squarely deftly coquetry fleshly halfpenny stealthy sullenly fidgety hostelry tensely trendy aplenty baronetcy libretti maidenly marquetry adeptly effendi ineptly friendly correctly intensely intently unfriendly apoplexy sacredly catalepsy deviancy preciously woodenly indirectly expressly incorrectly excellency confusedly complexly narcolepsy cognoscenti reassembly penitently grotesquely circumspectly equivalently ambivalently