How do i add up total costs for suppliers?

Hi there, 

Understanding your total costs for each supplier is important in order to stay on budget and informed. QuickBooks Online makes this easy to do, as you're able to run various reports to provide this information. I'll help by pointing you in the right direction. 

I recommend running the Purchases by Supplier Detail Report. To find this report, click the Reports tab on the left navigation menu, and search for the title in the search bar. 

Once you've retrieved the report, you can also explore the filtering options. You can select various date-ranges by adjusting the reporting period on the top left side of the report. You can also select Customize on the upper right side if you're looking for more options. 

I hope this helps you find what you're looking for. If there's anything else I can do to help, please let me know in the comments below.

Cheers!