Example 5 The license plates of motor vehicles in a city are consecutively numbered from "10000" to "99999". Among these 90000 license plates, the number of plates that contain at least one digit 9 and have the sum of their digits as a multiple of 9 is $\qquad$.

It is known that among them, there are 10000 numbers divisible by 9. Now consider the number of these 10000 numbers that do not contain the digit 9. Let the license plate number be $A B C D E$, and let the remainder of $A+B+C+D$ divided by 9 be $T$. Then, by taking $E=9-T$ (when $T=0$, take $E=0$), the requirement can be met. Thus, $A$ can take values from $1 \sim 8, B$ can take values from $0 \sim 8, C$ can take values from $0 \sim 8, D$ can take values from $0 \sim 8$. Once $A, B, C, D$ are determined, $E$ is also determined. Therefore, the number of such numbers without the digit 9 is $8 \times 9 \times 9 \times 9=5832$. Hence, the total number of license plates that meet the conditions is $10000-5832=4168$.