Scanning tunneling microscopy (STM) images of unstrained Si(001) and Si(001) grown tinder tensile strain have been analyzed to determine whether the Sg step energy increases with applied tensile strain, as predicted by Xie et al. [Phys. Rev. Lett. 73, 3006 (1994)]. We did this using "kink counting" of STM images, using a new "switch-kink" counting method that is better suited for analysis of STM images in which the local azimuthal miscut angle changes. Our measurements indicate that the S-B step energy does increase with tensile strain, in qualitative agreement with the predictions of Xie et al., although not as strongly as their calculations suggested.