Python random formatting issues

[Barnettch3]

Thanks guys for the quick replies i'll definitely use this information,
But its also not quite the issue i'm running into. Its that on two occasions when I have programmed something that involves formating a string or a list, it will work on 4 out of the 5 strings but there's one that just ignores it, everything is the same between them but it just doesn't change.

So for example one script I have 6 calculations that each returns a float and I want to round down so I use a round command.
It will work on 5 of them but the last one just returns the same number.

def dms_calc(DMS,DMS_Cost, Cost_Opinion):
    import math
    if DMS == "A":
        A = (0.187547-(0.01836*(math.log10(DMS_Cost/7.76))))
        A = round(A,4)
        print(A*100, "%")
        print("$",DMS_Cost*A)
    elif DMS == "B":
        B = (0.164145-(0.015303*(math.log10(DMS_Cost/7.76))))
        B = round(B,4)
        print(B*100, "%")
        print("$",DMS_Cost*B)
    
    elif DMS == "C":
        C = (0.142432-(0.010594*(math.log10(DMS_Cost/7.76))))
        C = round(C,4)
        print(C*100, "%")
        print("$",DMS_Cost*C)
    elif DMS == "D":
        D = (0.141419-(0.01236*(math.log10(DMS_Cost/7.76))))
        D = round(D,4)
        print(D*100, "%")
        print("$",DMS_Cost*D)
    elif DMS == "E":
        E = (0.118011-(0.009279*(math.log10(DMS_Cost/7.76))))
        E = round(E,4)
        print(E*100, "%")
        print("$",DMS_Cost*E)
    elif DMS == "F":
        F = (0.09521-(0.006301*(math.log10(DMS_Cost/7.76))))
        F = round(F,4)
        print(F*100, "%")
        print("$",DMS_Cost*F)

and the with the script I was talking about at the start it does the same were it will work on 80% of the lists but it just ignores some of them. It just seems like a bug and was wondering if anyone else had experience with something like this.