double to String problem

[Max Fedorov]

I designed a reporting engine that calculats totals at the end, so I needed
to convert double to String, in order to append it to a StringBuffer variable.

String text = new String().valueOf(double);

or

StringBuffer strBuf = new StringBuffer();
strBuf.append(double);
cell.addObject(new HTMLText(strBuf.toString()));

But after the convertion the value 6.20, for instance, becomes
6.199999999999998

Do you have any suggestions?
Thanx.