Hi Eric, Yes that's really easy. Just download the product inventory as a CSV file from your product admin, delete all the columns accept the pID and pPrice columns so those two columns will be column A and column B
Copy the prices to a new spread sheet in column A, then in the column B1 cell type =(A1*0.1)+A1 Fill down column B so 10 per cent is added to all the prices in column B
Finally copy column B over to your original CSV file and right click 'paste special' 'values' > save the file
Upload your CSV file using the update database option from the drop down.