The plural is रुपये, which I've heard pronounced similarly to how we say it in English.
Not quite. It is often pronounced रुपे (or sometimes रुपय) along with the 'correct' pronunciation रुपए/रुपये. It is almost never pronounced रुपी which is closest to the English pronunciation.
In parts of the Hindi Belt, people do pronounce रुपया like रुपैया. I know for a fact that no one ever says रुपया like rupee like "roo-pee". No self-respecting Hindi speaker, in their right mind, will ever say "roo-pee". You'll hear रुपया as "rūpya" or "rupai" and it doesn't matter if it's a "ek rupai" or "do rupai", singular or plural.