Is 5m 28 centimeters equal to 5.28m or 5.28 centimeters?

In value, yes. The extra zero on the end indicates a higher degree of precision. For example, 5.4 could really be 5.39, 5.43, 5.44, 5.36, etc. rounded to 5.4. That is because 5.4 has precision only to the tenths place so its error can be +/- 4 hundredths. However, 5.40 could only be off by 4 thousandths of an inch (5.403, 5.404, etc.), which makes 5.40 much more accurate than 5.4.