The sentence "all prices are in US Dollars" is correct and can be used in written English. You can use this sentence to communicate that all the prices within a given context are in US Dollars. For example, "If you are buying items from our store, please be aware that all prices are in US Dollars.".
(All prices are in United States dollars).
All prices are in United States dollars, which are widely accepted.
The pricing charged by the cloud providers are in US dollars per resource unit per usage hour.
Prices are expressed in US dollars unless otherwise specified.
(All prices are approximations in United States dollars).
Prices are in Singapore dollars before taxes. 1 Singapore dollar corresponds approximately to 0.8 US dollars.
Prices are in United States dollars, calculated at the rate of $1.50 Canadian to the United States dollar.
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