monetary units

Spell out the word “cents” in lowercase and use numerals for amounts less than a dollar.

Use the $ sign and numerals for larger amounts, except in casual references: The book cost $4. I have $3.05. Dad, give me a dollar.

For amounts exceeding $1 million, use the $ sign and numerals up to two decimal places: It is worth $4.45 million. A $2 million NIH grant.