1. If the mantissa of the shopping item is HK$ 9, Hui will bring at least 1 and two coins from 5 yuan and 2 yuan respectively;

2. If the mantissa of the purchased goods is HK$ 8, A Hui will bring at least 1, 1 and 1 coins from 5 yuan, 2 yuan and 0 yuan respectively.

3. If the mantissa of the purchased goods is HK$ 7, you will bring at least 1 coin and 1 coin from 5 yuan and 2 yuan respectively.

4. If the mantissa of the purchased goods is 6 yuan, you will bring at least 1 5-yuan coin and 1 0 yuan coin respectively.

5. If the mantissa of the purchased goods is HK$ 4, you should bring at least coins from 2 yuan.

6. If the mantissa of the purchased goods is HK$ 3, you will bring at least 1 2 yuan coin and 1 0 yuan coin respectively.

Because I only bought it three times, according to the above situation, according to the maximum demand, you only need to bring three coins from 5 yuan (each mantissa is more than 5 yuan), six coins from 2 yuan (each mantissa needs two 2 yuan) and three coins from 1 yuan (each mantissa is odd except 5 yuan, and coins from 1 yuan are needed).