Dennis, who lost the lead to Sagan after the world champion won his second consecutive stage on Thursday, gained a 16 second advantage over BMC team-mate Taylor Phinney.
Sagan slips to fourth with a deficit of 27 seconds, with 2010 race winner Tony Martin (Etixx-Quick Step) three seconds ahead of him.
Team Sky took advantage of a late rule change, meaning the clock stopped after the fourth rider rather than the fifth, to ship the lead weights and go down to their four strongest riders well before the finish.
The tactic worked, with the British squad beating Orica-BikeExchange’s leading time to temporarily take the top spot on the podium. Andre Greipel’s Lotto-Soudal squad were on hand to push ahead of the Brits, who were then passed by the likes of Movistar, IAM Cycling and LottoNL-Jumbo.
Dennis’s BMC squad then showed why they are the world team time trial champions by putting in a time of 23.11, finishing 34 seconds ahead of overnight leader Sagan and his Tinkoff team.
It was stage bragging rights and the race lead for BMC, who will look to stay ahead of Etixx for the third year running at the World Championships in Doha next month.
The 2016 Eneco Tour concludes on Sunday.
Eneco Tour stage five, Sittard-Geleen (21km TTT)
1. BMC (USA), 23-11
2. Etixx-Quick Step (Bel), at 6s
3. LottoNL-Jumbo (Ned), at 23s
4. Movistar (Esp), at 25s
5. IAM Cycling (Sui), at 26s
6. Lotto-Soudal (Bel), at 29s
7. Giant-Alpecin (Ger), at 33s
8. Tinkoff (Rus), at 34s
9. Team Sky (GBr), at 38s
10. FDJ (Fra), at 40s
Overall standings after stage five
1. Rohan Dennis (Aus) BMC, 13-40-47
2. Taylor Phinney (USA) BMC, at 16s
3. Tony Martin (Ger) Etixx-Quick Step, at 24s
4. Peter Sagan (Svk) Tinkoff, at 27s
5. Niki Terpstra (Ned) Etixx-Quick Step, st
6. Jos van Emden (Ned) LottoNL-Jumbo, at 28s
7. Manuel Quinziato (Ita) BMC, at 29s
8. Greg Van Avermaet (Bel) BMC, at 33s
9. Bob Jungels (Lux) Etixx-Quick Step, at 36s
10. Marcel Kittel (Ger) Etixx-Quick Step, at 37s