solidity - 我将如何在 Solidity 中实施买卖转让税

Question

我想在我的代码中加入转让税，但不知道如何去做。我将对买卖征收 2.5% 的税。任何帮助/建议将不胜感激。这是我到目前为止所拥有的：

pragma solidity ^0.8.4;

contract Token {
    mapping(address => uint) public balances;
    mapping(address => mapping(address => uint)) public allowance;
    uint public totalSupply = 100000000000 * 10 ** 18;
    string public name =  "*****";
    string public symbol = "****";
    uint public decimals = 18;
    
    event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);
    
    constructor(){
        balances[msg.sender] = totalSupply;
    }
    
    function balanceOf(address owner) public view returns(uint){
        return balances[owner];
    }
    function transfer(address to, uint value) public return(bool){
        require(balanceOf(msg.sender) >= value, 'balance too low');
        balances[to] += value;
        balances[msg.sender] -= value;
        emit Transfer(msg.sender, to, value);
        return true;
    }

function transferFrom(address from, address to, uint value) public returns(true){
    require(balanceOf(from) >= value, 'balance too low');
    require(allowance[from][msg.sender] >= value, 'allowance too low');
    balances[to] +=value;
    balances[from] -= value;
    emit Transfer (from, to, value);
    return true
    }

function approve (address spender, uint value) public reutrns(bool) {
    allowance[msg.sender][spender] = value;
    emit Approval(msg.sender, spender, value);
    return true;
    }

}