Modern theoretical models of molecular junctions often combine density functional theory (DFT) and non-equilibrium Green's functions (NEGF) methods. While widely utilized, DFT-NEGF methods present their own challenges, such as overestimating the conductance of molecular junctions, sometimes by orders of magnitude likely due to the use of generalized gradient approximation (GGA) functionals. The computed conductance could be more closely aligned with experimental results by taking advantage of higher-level functionals, especially range-separated hydrid functionals, as demonstrated by the Dunietz group. However, due to the utilization of periodic DFT with plane-wave basis sets, DFT-NEGF methods incur considerable computational cost when climbing the Jacobs ladder of density functionals. Here, we present a quantum tunneling model of coherent transport to calculate the conductance of benzene-based singlemolecule junctions. While single-level tunneling models of transport, such as the Simmons model, exist in the literature and are routinely used by experimental groups to extract conductance and current properties at the molecular level from their measurements, we develop a modified tunneling model that includes the effective mass of the transporting charge. Further, we calculate each parameter in the model using DFT and do not use any empirical parameters. We apply our model to study coherent transport in benzene-1,4-dithiol and benzene-1,4-diamine junctions bound to gold, silver and copper electrodes, in which transport is hole-dominated due to the presence of electron-donating linker groups on the aromatic ring. We show that the use of rangeseparated hybrid functionals lead to more accurate conductance predictions due to a better description of the long-range charge transfer across the metal-molecule-metal junction. Overall, our tunneling model combined with DFT presents an efficient, holistic, and quite accurate theoretical approach to study the effects of the molecule-electrode interface on the important electrical and mechanical properties of single-molecule junctions that undergo coherent transport.