Как убрать погрешность при использовании double в вычислениях?

#include <algorithm>
#include <iostream>
#include <numeric>
#include <vector>

using namespace std;
const double percent = 5.023;
long double fn(const long double &one,const long double &two)
{
    return ((one + two) / 100) * percent;
}
int main()
{
    vector<long double> v;

    for(int i=0;i<=10000;++i)
    {
        v.push_back(i);
    }

    sort(v.begin(),v.end());
    partial_sum(v.begin(), v.end(), v.begin(),fn);
    long double sum = std::accumulate(v.begin(), v.end(), 0);
    cout<<sum<<endl; //2.63956e+06
    return 0;
}

#include <iostream>
#include <numeric>
#include <set>
#include <algorithm>
#include <iterator>
using namespace std;

const double percent = 5.023;
typedef long double ddouble;
typedef multiset<ddouble> DblSet;

int main() {

    int size = 10;
    ddouble *d = new ddouble[size];
    for(int i=0;i<size;++i)
    {
        d[i]=i;
    }
    DblSet myset(d,d+size);
    ostream_iterator<ddouble> output( cout, " ");

    while(myset.size()!=1)
    {
        ddouble a = *myset.begin();
        myset.erase(myset.begin());
        ddouble b = *myset.begin();
        myset.erase(myset.begin());
        myset.insert(myset.begin(),((a+b)/100)*percent);
    }

    copy(myset.begin(),myset.end(),output);
    delete d;
    return 0;
}