TreeMap + ExtractDataFromXLSX

import java.io.FileInputStream;
import java.util.Locale;
import java.util.TreeMap;

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExtractDataFromXLSX {

    public static void main(String[] args) {
        Locale.setDefault(Locale.ROOT);
        try (FileInputStream input = new FileInputStream("Incomes-Report.xlsx")) {
            XSSFWorkbook wb = new XSSFWorkbook(input);
            XSSFSheet sheet = wb.getSheet("Incomes");
            TreeMap<String, Double> allOffices = new TreeMap<String, Double>();
            double totalIncome = 0;

            XSSFRow currentRow = sheet.getRow(1);
            while (currentRow != null) {
                XSSFCell officeCell = currentRow.getCell(0);
                String currentOffice = officeCell.getStringCellValue();
                XSSFCell incomeCell = currentRow.getCell(5);
                double currentIncome = incomeCell.getNumericCellValue();
                totalIncome += currentIncome;
                if (allOffices.containsKey(currentOffice)) {
                    currentIncome += allOffices.get(currentOffice);
                }
                allOffices.put(currentOffice, currentIncome);
                currentRow = sheet.getRow(1 + currentRow.getRowNum());
            }
            for (String office: allOffices.keySet()) {
                double income = allOffices.get(office);
                System.out.printf("%s -> %.2f", office, income);
                System.out.println();
            }
            System.out.println("Grand Total -> " + totalIncome);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}