How to round to specific values in Python

I am working on an algorithm to automatically create character sheets for a roleplaying game. In the game, you have attributes which you put points into to increase them. However, at a certain value it takes 2 points to increase the value of the actual attribute by 1. You start of with a certain number of points, and each attribute has a value of 1 by default

I have a program that randomly assigns the points, however I am stuck as to how I then change these values (that are in a dictionary) to round down when necessary.

For example, if I put 3 points in "strength", thats fine, I get a "strength" value of 3 (including tha base 1). However, if I put 4 points in, I still should only have a value of 4. It should take 5 points (plus the base 1) in order to get a value of 5. It then takes another 2 points to get a value of 6, 3 points to get a value of 7 and 3 points to get a value of 8.

The code I am currently using to assign the attibutes looks like this:

attributes = {}
row1 = ['strength', 'intelligence', 'charisma']
row2 = ['stamina', 'willpower']
row3 = ['dexterity', 'wits', 'luck']

def assignRow(row, p): # p is the number of points you have to assign to each row
    rowValues = {}
    for i in range(0, len(row)-1):
        val = randint(0, p)
        rowValues[row[i]] = val + 1
        p -= val
    rowValues[row[-1]] = p + 1
    return attributes.update(rowValues)

assignRow(row1, 7)
assignRow(row2, 5)
assignRow(row3, 3)

What I want is just a simple function that takes the dictionary "attributes" as a parameter, and converts the number of points each attribute has to the proper value it should be.

i.e. "strength": 4 stays as "strength": 4, but "wits": 6" goes down to "wits": 5", and "intelligence: 9 goes down to "intelligence: 7".

I'm somewhat new to using dictionaries and so the ways I would normally approach this:

def convert(list):
    for i in range(len(list)):
        if list[i] <= 4:
            list[i] = list[i]
        if list[i] in (5, 6):
            list[i] -= 1
        if list[i] in (7, 8):
            list[i] -= 2
        if list[i] in (9, 10):
            list[i] = 6
        if list[i] in (11, 12, 13):
            list[i] = 7
        else:
            list[i] = 8

Not efficient or pretty but still a solutuion. However, you can't just loop over indexes in a dictionary so I am not entirely sure how to go about something like this.

General explanation or function would be appreciated.