  The tunneling conductance spectra of a normal metal / insulator / singlet
superconductor is calculated from the reflection amplitudes using the
Blonder-Tinkham-Klapwijk (BTK) formulation. The pairing symmetry of the
superconductor is assumed to be $d_{x^2-y^2}+is$, or $d_{x^2-y^2}+id_{xy}$. It
is found that in the ($d_{x^2-y^2}+is$)-wave case there is a well defined
conductance peak in the conductance spectra, in the amplitude of the secondary
s-wave component. In the ($d_{x^2-y^2}+id_{xy}$)-wave case the tunneling
conductance has residual values within the gap, due to the formation of bound
states. The bound state energies depend on the angle of the incident
quasiparticles, and also on the boundary orientation. On the basis of this
observation an electron focusing experiment is proposed to probe the
($d_{x^2-y^2}+id_{xy}$)-wave state.
