C# :: Checkbox Columns In DataGridView

Ok so I'm working with a windows form in C# and sql server database. I'm trying to do something like what is in the image below using a datagridview. My question is how do I 1) ensure only 1 checkbox is checked per row 2) do math that 'links' a checkbox column with another column, and add the totals. I understand that asp.net and web forms would be easier but we have not reached that point in the course yet. Would this be on the right track:

foreach (DataGridViewRow row in dataGridView.Rows)
{
if ((bool)(row.Cells["Checkbox"]).Value || (CheckState)row.Cells["Checkbox"].Value == CheckState.Checked)
{
// Do something
}
}
Attached image(s)