gan, gimana ya codding nyaa kl untuk mencari total dgn rumus "total=jumlah seluruh hasil perhitungan

ini codding ane,

#include <cstdlib>
#include <iostream>
#include <iomanip>

using namespace std;

typedef struct
{
int banyak;
char kode[10],nama_barang[20],satuan[5];
long double harga,jumlah,total,diskon,bayar;
} brg;
typedef struct
{
int no_faktur;
char tgl[10],nama[20],alamat[50];
} data;

int main(int argc, char *argv[])
{
awal:
system("cls");
data z;
int a,i;
char input;
cout<<"Masukkan Data"<<endl;
cout<<"-------------"<<endl<<endl;
cout<<"No Faktur : ";cin>>z.no_faktur;
cout<<"Tanggal : ";fflush(stdin);cin.get(z.tgl,10);
cout<<"Nama Pembeli : ";fflush(stdin);cin.get(z.nama,20);
cout<<"Alamat : ";fflush(stdin);cin.get(z.alamat,50);
cout<<"Jumlah Barang Yang Di Beli = ";cin>>a;
system("cls");
brg x[10];
for (i=1;i<=a;i++){
cout<<"Pembelian Ke-"<<i<<endl;
cout<<"Kode Barang : ";fflush(stdin);cin.get(x[i].kode,10);
cout<<"Nama Barang : ";fflush(stdin);cin.get(x[i].nama_barang,20);
cout<<"Banyaknya : ";cin>>x[i].banyak;
cout<<"Satuan : ";fflush(stdin);cin.get(x[i].satuan,5);
cout<<"Harga : ";cin>>x[i].harga;
cout<<endl;}
//output
system("cls");
cout<<"============FAKTUR PEMBELIAN BARANG=============="<<endl;
cout<<"============INTEL COMPUTER BERJAYA==============="<<endl;
cout<<"==========JALAN MERANTI NO. 16 BINJAI============"<<endl;
cout<<"-------------------------------------------------"<<endl<<endl;
cout<<"No Faktur : "<<z.no_faktur<<endl;
cout<<"Tanggal : "<<z.tgl<<endl;
cout<<"Nama Pembeli : "<<z.nama<<endl;
cout<<"Alamat : "<<z.alamat<<endl;
cout<<"------------------------------------------------------------------"<<endl;
cout<<"No. Kode Barang Nama Barang Satuan Harga Banyak Jumlah"<<endl;
cout<<"------------------------------------------------------------------"<<endl;
for(i=1;i<=a;i++){
cout<<setiosflags(ios::left)<<setw(5)<<i;
cout<<setiosflags(ios::left)<<setw(13)<<x[i].kode;
cout<<setiosflags(ios::left)<<setw(13)<<x[i].nama_barang;
cout<<setiosflags(ios::left)<<setw(9)<<x[i].satuan;
cout<<setiosflags(ios::left)<<setw(9)<<x[i].harga;
cout<<setiosflags(ios::left)<<setw(8)<<x[i].banyak;
x[i].jumlah=x[i].harga*x[i].banyak;
cout<<setiosflags(ios::left)<<setw(8)<<x[i].jumlah;
cout<<endl;}
cout<<"------------------------------------------------------------------"<<endl;
cout<<endl;
for(i=1;i<=a;i++){
x[i].total=x[i].jumlah+x[i].jumlah;}
x[i].diskon=10;
x[i].bayar=x[i].total-x[i].diskon;
cout<<"Total Pembelian : Rp."<<x[i].total<<endl;
cout<<"Diskon : Rp."<<x[i].diskon<<endl;
cout<<"Bayar : Rp."<<x[i].bayar<<endl;
cout<<endl;
cout<<"Input data lagi <Y/T> :"; cin>>input;
if (input=='y'||input=='Y')
goto awal;
else
goto akhir;
akhir:
return EXIT_SUCCESS;
}

tolong di bantu gan