访问私有对象数据时出现问题

所以我正在为我的OO类做这个项目。我们需要创建两个类，销售和注册。我写过Sale和Register的大部分。我唯一的问题（目前）是我似乎无法从我的注册类访问销售对象的私有成员数据。

销售标题：

enum ItemType {BOOK, DVD, SOFTWARE, CREDIT};
class Sale
{
public:
Sale();         // default constructor, 
            // sets numerical member data to 0
void MakeSale(ItemType x, double amt);  
ItemType Item();        // Returns the type of item in the sale
double Price();     // Returns the price of the sale
double Tax();       // Returns the amount of tax on the sale
double Total();     // Returns the total price of the sale
void Display();     // outputs sale info (described below)
private:
double price;   // price of item or amount of credit
double tax;     // amount of sales tax (does not apply to credit)
double total;   // final price once tax is added in.
ItemType item;  // transaction type
};

寄存器标头：

class Register{
public:
Register(int ident, int amount);
~Register();
int GetID(){return identification;}
int GetAmount(){return amountMoney;}
void RingUpSale(ItemType item, int basePrice);
void ShowLast();
void ShowAll();
void Cancel();
int SalesTax(int n);
private:
int identification;
int amountMoney;
int listSize = 5;
int numSales;
Sale* sale;
};

所以我现在正在尝试编写RingUpSale()函数，但我似乎无法访问私有字段。这是我的代码：

void Register::RingUpSale(ItemType item, int basePrice){
if(numSales == listSize){
        listSize += 5;
        Sale * tempArray = new Sale[listSize];
        memcpy(tempArray, sale, numSales * sizeof(Sale));
        delete [] sale;
        sale = tempArray;
    }
    sale[numSales]->item = item; //this works for some reason
    sale[numSales]->total = basePrice; // this doesn't
    if(item == 'CREDIT'){ 
            sale[numSales]->tax = 0; // and this doesn't
            sale[numSales]->total = basePrice; // and neither does this
            amountMoney -= basePrice;
    }
    ++numSales;
}

尝试设置销售对象的总计和税项字段在 Eclipse 中出现错误：

"Field 'total' cannot be resolved"

我不确定为什么会这样或如何解决它。任何帮助将不胜感激。是的，我已经在必要时添加了#include "sale.h"和#include "register.h"。