How do you like the EURO?

If you want to buy something for less than 100 Euro you can pay with different 'units' (coins and bills).
At the moment the 6 best existing units to use are: 1, 2, 5, 10, 20 and 50.

If you want to buy something (that is less than 100 Euro) you have to use some of those units to pay for it.

Now let's go shopping with these 6 units :)
You are going to search for products that are 1 euro untill 99 euro, and you are going to buy one of each. Each time you buy something you choose as less units as possible (you have an infinite amount of units).

Let's see how many units we need if we use the units 1, 2, 5, 10, 20 and 50:

1 EURO -> only 1 unit: 1
2 EURO -> 1 unit : 2
3 EURO -> 2 units : 1 + 2
..
..
..
98 EURO -> 6 units : 1 + 2 + 5 + 20 + 20 + 50
99 EURO -> 6 units : 2 + 2 + 5 + 20 + 20 + 50

Now we will take the average of the needed units between 1 and 99, which is 3.4 units.
That's quite alright, but we can do better...

Your job is to find the lowest average with 6 different (integer) units.
Maybe a 3 euro coin is a good idea? And what about a 22 euro bill? Try it out :)

Enter your answer below like this => 1:2:5:10:20:50 (example).
So from the lowest to the highest unit with a ':' in between.