5. There are two uniform small cubes $A$ and $B$. The six faces of cube $A$ are labeled with the numbers $1, 2, 3, 4, 5, 6$; the six faces of cube $B$ are labeled with the numbers $1, 1, 2, 3, 4, 6$. Xiao Guang rolls cube $A$, and the number facing up is $x$; Xiao Ming rolls cube $B$, and the number facing up is $y$. Then the point $Q(x, y)$ determined by their respective rolls landing on the hyperbola $y=\frac{6}{x}$ has a probability of ( ).
(A) $\frac{1}{6}$
(B) $\frac{1}{9}$
(C) $\frac{1}{12}$
(D) $\frac{5}{36}$
5.D.

List 1.
Table 1
\begin{tabular}{|c|c|c|c|c|c|c|}
\hline$x$ & 1 & 2 & 3 & 4 & 5 & 6 \\
\hline$y$ & $(1,1)$ & $(2,1)$ & $(3,1)$ & $(4,1)$ & $(5,1)$ & $(6,1)$ \\
\hline 1 & $(1,1)$ & $(2,1)$ & $(3,1)$ & $(4,1)$ & $(5,1)$ & $(6,1)$ \\
\hline 2 & $(1,2)$ & $(2,2)$ & $(3,2)$ & $(4,2)$ & $(5,2)$ & $(6,2)$ \\
\hline 3 & $(1,3)$ & $(2,3)$ & $(3,3)$ & $(4,3)$ & $(5,3)$ & $(6,3)$ \\
\hline 4 & $(1,4)$ & $(2,4)$ & $(3,4)$ & $(4,4)$ & $(5,4)$ & $(6,4)$ \\
\hline 6 & $(1,6)$ & $(2,6)$ & $(3,6)$ & $(4,6)$ & $(5,6)$ & $(6,6)$ \\
\hline
\end{tabular}

Among these, the points $(1,6),(2,3),(3,2),(6,1)$ lie on the hyperbola $y=\frac{6}{x}$.
Therefore, the required probability is $\frac{5}{36}$.