This behavior appears because the label's position is centered to the corresponding tick. In order to offset the last label you can define a LabelTemplate and use an IValueConverter to set a Margin based on the value of the label. You can see this approach demonstrated in the attached project.
However, keep in mind that re-positioning the label could confuse the end user, because the new position won't be relative to its tick. Instead of re-positioning the label you can also consider hiding it. Or just allocate more space for the scale so that the label's extending outside the boundaries doesn't interfere with the rest of the UI. Another approach which you can try is to disable the labels rotation, thus positioning them horizontally. You can do that by setting the LabelRotationMode property to None.
I hope those suggestions help.
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