Need to load more than 2 decimal places

Hello,

1. We are loading exchange rates to planning from a file through data management and the values in rates column have 14 decimal places(Ex values: .73172146606776, 1.29416076088267) and we need to have all those 14 decimal places but only 2 decimal places are getting loaded.
2. Can we load data from .xlsx file through data management with tab delimiter because we are getting source file in .xlsx format? (OR) To use tab delimiter, do I need to save the .xlsx file as .txt? When I am using .xlsx file with tab delimiter, import step is getting failed and when I use .txt file with tab delimiter, it is successfully importing.