You can pay for your purchase with eTunai at the merchants below :

Babu's Kitchen (Bandar)
Starbucks Brunei (Mabohai)
Sapphira Cafe & Restaurant (All branches)
CheezBox Cafe & Restaurant (The Mall Gadong)
Gong Cha (Kiulap, Freshco & Airport Mall)
Charcoal BBQ & Grill (All branches)
Excapade (All branches except Kiulap)
The Coffee Bean and Tea Leaf (All branches except Airport)
OHSO Kidswear (The Mall Gadong)
QQeStore (All branches)
The Body Shop (The Mall Gadong)
Max Centre (Sin Hup Huat Gadong)
Michelin Centre (Sin Hup Huat Gadong)
Fish and Co. (Citi Square)
Kitaro Japanese Restaurant (Centerpoint)
Starhome (Mata-Mata)
Chatterbox Kopitiam (Gadong)
Euroclassic (Centerpoint)
Nur Ammanie (All branches)
Homeselect (Sengkurong)
Fabrica (All branches)
Country Patch (All branches)
Dee Jay (All branches)
First Emporium (Jalan Tutong)
Bali Paradise (Kiulap)
Perfect Vision (Kiulap)
I-Lotus Restaurant (Tungku)
Samima Bookstore (Kiulap)
Home Suite Home (Kiulap)
Bello Cafe (Kiulap)
Laqvin (The Mall Gadong)
Waroeng Penyet (All branches)
Gloria Jean's Coffees (Freshco)
Sushi Tei (Gadong Central)
Auntie Anne's (Freshco)
All Seasons Restaurant (All branches)
Pastamania (All branches)
Current Newspaper (All branches)
A.Ayam Restaurant (Bengkurong)
Liang Toon (Bengkurong)
Neo Metro (All branches)
Zen Spa (All branches)
Shabulicious (Batu Besurat)
Modesto Bistro & Grill (Batu Besurat)
Lof Bakery (All branches except Yayasan)
Ximply Chriz Cafe (Kiulap)
Shavu & Grill (Kuala Belait)
GadgetPlus E-Store (The Mall)
Mobileone (Citi Square)
Ikura Sushi (Gadong Central)
Kokokan Ayam Restaurant (Gadong)
SCR Express (Citi Square)
Takaful Brunei Am (Bandar)
Buccaneer Restaurant (Kuala Belait)

Click here to download the guide on how to register and use eTunai.