How to apply CSS page-break to print a table with lots of rows?

You can use the following:

<style type="text/css">
   table { page-break-inside:auto }
   tr    { page-break-inside:avoid; page-break-after:auto }
</style>

Refer the W3C's CSS Print Profile specification for details.

And also refer the Salesforce developer forums.

Wherever you want to apply a break, either a table or tr, you needs to give a class for ex. page-break with CSS as mentioned below:

/* class works for table row */
table tr.page-break{
  page-break-after:always
} 

<tr class="page-break">

/* class works for table */
table.page-break{
  page-break-after:always
}

<table class="page-break">

and it will work as you required

Alternatively, you can also have div structure for same:

CSS:

@media all {
 .page-break  { display: none; }
}

@media print {
 .page-break  { display: block; page-break-before: always; }
}

Div:

<div class="page-break"></div>