Example of a table with round borders:

Small radius

Text-text-text-text Text-text-text-text Text-text-text-text Text-text-text-text Text-text-text-text Text-text-text-text

Larger radius

Text-text-text-text Text-text-text-text Text-text-text-text Text-text-text-text Text-text-text-text Text-text-text-text

The key is in the CSS style "border-radius".
code for the above examples:
style="border-style: solid; border-width: 1px; border-radius: 50px; border-color: #f00;"