For me, the Twitter Bootstrap Solution looks good. It excludes IE < 9 (no round corners in IE 8 and lower), but that's O.K. I think, if you develop prospective Web-Apps.
CSS/HTML:
table { _x000D_
border: 1px solid #ddd;_x000D_
border-collapse: separate;_x000D_
border-left: 0;_x000D_
border-radius: 4px;_x000D_
border-spacing: 0px;_x000D_
}_x000D_
thead {_x000D_
display: table-header-group;_x000D_
vertical-align: middle;_x000D_
border-color: inherit;_x000D_
border-collapse: separate;_x000D_
}_x000D_
tr {_x000D_
display: table-row;_x000D_
vertical-align: inherit;_x000D_
border-color: inherit;_x000D_
}_x000D_
th, td {_x000D_
padding: 5px 4px 6px 4px; _x000D_
text-align: left;_x000D_
vertical-align: top;_x000D_
border-left: 1px solid #ddd; _x000D_
}_x000D_
td {_x000D_
border-top: 1px solid #ddd; _x000D_
}_x000D_
thead:first-child tr:first-child th:first-child, tbody:first-child tr:first-child td:first-child {_x000D_
border-radius: 4px 0 0 0;_x000D_
}_x000D_
thead:last-child tr:last-child th:first-child, tbody:last-child tr:last-child td:first-child {_x000D_
border-radius: 0 0 0 4px;_x000D_
}
_x000D_
<table>_x000D_
<thead>_x000D_
<tr><th>xxx</th><th>xxx</th><th>xxx</th></tr>_x000D_
</thead>_x000D_
<tbody>_x000D_
<tr><td>xxx</td><td>xxx</td><td>xxx</td></tr>_x000D_
<tr><td>xxx</td><td>xxx</td><td>xxx</td></tr>_x000D_
<tr><td>xxx</td><td>xxx</td><td>xxx</td></tr>_x000D_
<tr><td>xxx</td><td>xxx</td><td>xxx</td></tr>_x000D_
<tr><td>xxx</td><td>xxx</td><td>xxx</td></tr>_x000D_
</tbody>_x000D_
</table>
_x000D_
You can play with that here (on jsFiddle)