Multi-Currency in Bill.com only applies to Accounts Payable.

If Multi-Currency has not been enabled:

From Oracle NetSuite to Bill.com

• Payables transactions in Oracle NetSuite that are not in USD (US dollar) will not sync to Bill.com, unless Multi-Currency is enabled in Bill.com
• Receivables transactions in Oracle NetSuite that are not in USD will not sync to Bill.com

From Bill.com to Oracle NetSuite

• Payables transactions in Bill.com will always sync to Oracle NetSuite in USD, unless Multi-Currency is enabled in Oracle NetSuite