At least in America (where the primary coin has been the 25c 'quarter' for decades, with pennies only muddying up the currency playing field), it's typically much easier for most players to deal with increments (and multiples) of 25 than either 1 or 5.

Compare an opening raise of 3x followed, by a 3x 3-bet and a 2x 4-bet:

1/2 -- raise to 6, re-raise to 18, 4-bet to 36

2/4 -- raise to 12, re-raise to 36, 4-bet to 72

vs

5/10 -- raise to 30, re-raise to 90, 4-bet to 180

10/20 -- raise to 60, re-raise to 180, 4-bet to 360

vs

25/50 -- raise to 150, re-raise to 450, 4-bet to 900

50/100 -- raise to 300, re-raise to 900, 4-bet to 1800

Values of 150, 300, 450, 900, and 1800 are much easier for most players to calculate and construct using 25/100/500/1000 chips, compared to 6, 12, 18, 36, and 72 values using 1/5/25 chips, or 30, 60, 90, 180, and 360 values using 5/25/100 chips.

And that's just two early levels; it gets progressively worse as T1- and T5-base blinds get larger and less 'standard'.