Halo 5: Guardians sold and estimate 1.5 million copies on first week worldwide at retail. This is an estimate by VGChartz Weekly Chart.
The numbers in the regions suggest that nearly two thirds of sales came from the US. While a quarter of sales came from Europe.
This were the estimates
This Is How The Sales Stack To Other Halo Franchises Week One Releases:
Halo CE: .90 million
Halo 2: 1.70 million
Halo 3: 3.80 million
Halo: Reach: 3.70 million
Halo 4: 3.65 million
Halo 3 ODST: 2.20 million
Halo 5: 1.5 million
Halo TMCC: 0.90 million
Halo 1 Anniversary: 0.73 million
Halo Wars: 0.60 million
I think it is important to mention that the first two halo games came out in a time when the original Xbox came out and very few units were out.
Halo 5 Guardians was released October 27 Exclusively on the Xbox One