Those links do not have specific classes so you will need to use some CSS magic to target them separately.
For example this should do the trick:
a.give-donor-dashboard-tab-link.give-donor-dashboard-tab-link:nth-of-type(3n) {
border-bottom-right-radius: 20px;
border-bottom-left-radius: 20px;
}
We understand that there is a fine line between what is considered support & modifications. So while we will try help you with any type of query (support or modification), we can’t provide extensive help in terms of modifications. If you are requesting modification help, we’ll be glad to assist you a few lines of code. If however, your query requires more than that amount of code to be published, then you’ll need to get customization help.
This article covers some of the basics of using the inspect tool in your browser for doing some basic customization: https://www.wpbeginner.com/wp-tutorials/basics-of-inspect-element-with-your-wordpress-site/