Well, to avoid paying the resale levy of S$170K & also COV on resale flat, yet wanting a new flat, TS can consider getting DBSS or EC development which does not require TS to pay resale levy.
if TS sold his 5 room before 3 March 2006, his Resale levy is under old scheme, 25% for 5room. that could be why it is amounting to $100K+ http://www.hdb.gov.sg/fi10/fi10322p.nsf/w/SellFlatResaleLevy?OpenDocument