STEP # 01 : Make a Excel Sheet #
Make an excel sheet having these column to update MRP, tax type , Tax number
STEP # 02 : Go To All Import #
Open the All Import and click on the Upload File.
STEP # 02 : Upload File
After uploading the file then select Existing products if you are only updating product
STEP # 03: Manage Import #
On step three of import load a Template if you already have if not make a one its a drag & drop plugin
These custom fields you want to select to update MRP , Tax type & Price
STEP # 04 : Final Step #
These custom fields you want to add to update MRP , Tax type & Price
Tax Number: _tc_erp_tax_id
STEP # 05 : Then Import #
After this Import is done check the products.