Dots 5's may not be the correct indication for the table and since there is more than one table affected, there could be omissions for different reasons. Without the print page, it is impossible to tell. See Formats 11.6.4 and 11.6.5. Sometimes an omission in a table is indicated by dots 5's, sometimes by ellipses and sometimes with a dash. It depends on the nature of the omission. AND this question should be posted at the Math/Nemeth forum because Nemeth formatting takes precedence over general textbook formatting. Since this is a math book, I recommend that the math expert be consulted first to determine if there is a Nemeth format that should be followed.
IF and only IF it is determined that textbook guidelines apply and IF the same formatting applies to ALL the tables, you can inform the reader once on the TN page. However, the note you have suggested in your question would not work. A series of dot 5's (or ellipses, or a dash, whatever is the right one) indicates a blank entry. Where? A blank entry in what? This is the TN page at the beginning of the volume! When you write such a note be sure to give the reader all the information needed to understand what you are writing about. You can see that this will apply only to tables, but the reader can't possibly know that unless you say so.
And please don't forget to check with the Nemeth expert first.