To have the program round sales and purchase invoices automatically, you must activate the invoice rounding function.
Open the Sales & Receivables Setup window or the Purchases & Payables Setup window.
Click the General tab, and then place a check mark in the Invoice Rounding field.
Note that you can activate invoice rounding separately for sales and purchase invoices.
Setting Up G/L Accounts for Rounding Differences
Specifying G/L Rounding Accounts for Posting Groups
Setting Up Rounding Rules for Foreign Currency
Setting Up Rounding Rules for Local Currency