Appending the word 'degrees' to those heading figures where the heading ends in zero is not prescribed by ICAO. According to 5.2.1.4.1.1 of ICAO Annex 10, Volume II, a heading of 100 degrees is to be transmitted as 'heading one zero zero' and a heading of 080 degrees is to be transmitted as 'heading zero eight zero'.
The Manual of Radiotelephony (Doc 9432) goes even further and states in 3.1.3 of Chapter 3: 'The following words may be omitted from transmissions provided that no confusion or ambiguity will result: [...] b) "DEGREES" in relation to radar headings.'