12. (10 points) Xiaoming went to a store with 100 RMB to buy stationery. After returning home, he counted the RMB he got back, which included 4 different denominations of banknotes and 4 different denominations of coins. The banknotes were all worth more than 1 yuan, and the coins were all worth less than 1 yuan. Additionally, the sum of the values of all banknotes, in yuan, is divisible by 3, and the sum of the values of all coins, in fen, is divisible by 7. How much money did Xiaoming spend at most? (Note: The store has banknotes of 100 yuan, 50 yuan, 20 yuan, 10 yuan, 5 yuan, and 1 yuan, and coins of 5 jiao, 1 jiao, 5 fen, 2 fen, and 1 fen for change)
【Analysis】According to the characteristic of numbers that can be divided by 3: the sum of the digits in each place can be divided by 3, $50+20+10+1$ $=81$ yuan, $50+10+5+1=66$ yuan, $20+10+5+1=36$ yuan, all can be divided by 3, taking the smallest number is 36 yuan, which can be divided by 7, is a multiple of 7, $50+10+2+1=63$ points, and then add them up.

【Solution】Solution: Can be divided by 3, $50+20+10+1=81$ yuan, $50+10+5+1=66$ yuan, $20+10+5+1=36$ yuan,

Take the smallest number is 36 yuan,
Can be divided by 7 is $50+10+2+1=63$ points,
36 yuan + 63 points $=36$ yuan 6 jiao 3 fen,
100 yuan - 36 yuan 6 jiao 3 fen $=63$ yuan 3 jiao 7 fen;
Answer: Xiao Ming used at most 63 yuan 3 jiao 7 fen.