Linq中grouby sum小数位不对（类似与float的误差）,该怎么处理

Linq中grouby sum小数位不对（类似与float的误差）
下面是代码，Model中数值是double类型 但是sum的结果出现是item.Sum = 27.279999999999998
正确结果应该是27.27 后面那些数字为什么多出来了

 List<ProductModel> product = new List<ProductModel>();
            product.Add(new ProductModel
            {
                Id = 1,
                EnergyId = 2,
                Total = 5.34
            });
            product.Add(new ProductModel
            {
                Id = 1,
                EnergyId = 2,
                Total = 5.63
            });
            product.Add(new ProductModel
            {
                Id = 1,
                EnergyId = 2,
                Total = 5.65
            });
            product.Add(new ProductModel
            {
                Id = 1,
                EnergyId = 2,
                Total = 5.72
            });
            product.Add(new ProductModel
            {
                Id = 1,
                EnergyId = 2,
                Total = 4.94
            });
            var query = from p in product
                        group p by new
                        {
                            p.Id,
                            p.EnergyId
                        } into g
                        select new
                        {
                            g.Key,
                            Sum = g.Sum(p => p.Total)
                        };
            foreach (var item in query)
            {
               var sum = item.Sum;
            }

------解决思路----------------------
https://msdn.microsoft.com/zh-cn/library/system.double.aspx
精度问题，你应该用Math.Round指定精度，而且你的sum应该是27.28
------解决思路----------------------
5.34 + 5.63 + 5.65 + 5.72 + 4.94 = 27.28
Math.Round(27.279999999999998, 2) = 27.28
没有什么很正常
那个 5.63 被 2 除就是无限循环小数，放在计算机里，截尾了 自然是要小一点的