Tyme offers to types of plugins for GrandTotal:
When activated, Tyme automatically sends all billable time entries to GrandTotal. You can see all time entries in GrandTotal > Overview > Tyme (in the left sidebar).
When you create an invoice from these time entries, they are automatically marked as billed in Tyme. After the invoice has been marked as paid in GrandTotal, Tyme will also mark the related time entries as paid.
In GrandTotal you will see a new entry Send to Tyme when you right click a draft invoice. This action sends the items from the offer to Tyme and creates the client, project and tasks including hourly rates and estimates.