We can use (?string.currency) in the email template of the netsuite.The most basic way to format a number as Currency is to add ?string.currency onto the end of the variable that is being used. This will bring any numbers to 2 decimal places and will also put a $ next to the number. Also, negative numbers will no longer have a – in front of them and will instead be surrounded by parentheses.
For eg:- If you want to put $ sign infront of Total Amount then: ${transaction.amountTotal?string.currency}