There is no "extra" break; the listing is set for three per row, but the stylesheet has too much margin on the elements so only two can fit. In the stylesheet.css, find this rule
Code:
/*list box contents*/
.centerBoxContents, .specialsListBoxContents, .categoryListBoxContents, .additionalImages, .centerBoxContentsSpecials, .centerBoxContentsAlsoPurch, .centerBoxContentsFeatured, .centerBoxContentsNew {
margin: 1em 1em;
}
and either remove .categoryListBoxContents, or change the second 1em to 0. You may also want to remove other elements from the rule if there are other listings that misbehave.