I have several savings accounts with one institution. Do I have enter each one separately or can I enter the grand total

Yes, you can.  The IRS is going to look for the total.  However, keep good documentation.  In the event something was missed, you will have to be able to reconstruct what you did.

My answer would be "yes" as long as each of the investments, or savings accounts, is all under the same tax ID or social security number.