When issuing invoices the gst is calculating incorrect. for instance when i issue an invoice for $450, the gst calculates as $45.01 or $45.02 or similar. how to fix?

Hi scottm-worklegal,

QuickBooks Online automatically calculates the GST amount based on the Amount, GST rate selected and if it is set to Exclusive or Inclusive of tax on your invoice. 

If there's a need to change the GST amount calculated on the invoice, you can change it on the GST field. Please see screenshot of a dummy invoice below for your reference. 

Feel free to reply in this thread if you have any more questions about this.