optics - Does total internal reflection really reflect every single photon?

In certain cases of refraction, light can be totally internally reflected (TIR) instead of being transmitted. One learns that literally 100% of the light is reflected back in such an interaction.

My question is simple: To what degree is this true? Certainly, geometric imperfections could effectively lead to different geometry outside the TIR regime, but are there other effects? Tunneling? Photon-photon interaction? Interference? If so, about what strength are they ($1:10^3$, $1:10^6$, $1:10^{18}$, ...)?