xml parse in postgresSQL
if I correct I understand You - Your problem is single row in result
You can use unnest function for return all values

EDIT Text of query after questions from author:

DO $$

DECLARE xml_string xml;

BEGIN
xml_string := XMLPARSE(DOCUMENT convert_from(pg_read_binary_file('MyData.xml'), 'UTF8'));



DROP TABLE IF EXISTS my;
CREATE TABLE my AS 
SELECT
    unnest(xpath('//ID/text()', xml_string)) as ID,
    unnest(xpath('//Name/text()', xml_string)) as Name,
    unnest(xpath('//ID_CUSTOMER/text()', xml_string)) as ID_CUSTOMER;

END$$



SELECT * FROM my;

1   IT  1
1   IT  2
1   IT  3
1   IT  4
1   IT  5