There is a time rounding option, so you can track in fifteen minutes increments if you want.

This software does not create invoices. I manually import information into an invoice, but you can print out a worksheet showing your hours and calculated costs. It hasn't seemed worth the effort for me to try, but I wouldn't be surprised if you could figure out a way to export the data to an invoice in Excel.

What I do is start a file for each new client. You enter the hourly rate, then you just click the timer to start timing. At the end of a project (or a week-depending on how you bill) you’ll have a calculated total of hours and costs. This makes my invoicing pretty painless. The calculations have already been done and I have a nice spreadsheet to share with clients if they wish to see a log of my hours.