Weird behavior in the SUM column

As I was testing, I noticed a weird behavior in the SUM column.
The generated (from the script) column only sums the integer part of the numbers, while the column I added manually, sums correctly the decimal parts.
(In the image "Total sum of Total" is the generated column, while "GrandTotal" is the column I added manually).
 
Is there something I need to do in the script code??
 
The code for the report I am using:

report: {
dataSource: {data: jsonData},
slice: {
rows: [
{uniqueName: "TaxNumber"},
{uniqueName: "Company Name"}
],
measures: [{
uniqueName: "Total",
aggregation: "sum"
}],
expands: {
expandAll: true
}
},
options: {
grid: {
viewType: "grid",
type: "classic"
}
}
},

 
Kind regards,
Stelios