StrToDouble() and StringToDouble() adds unnecessary floating digits.

1. Floating-point has an infinite number of decimals, it's your not understanding floating-point and that some numbers can't be represented exactly. (like 1/10.)
             Double-precision floating-point format - Wikipedia, the free encyclopedia

   See also The == operand. - MQL4 programming forum

   If you want to see the correct number of digits, convert it to a string with the correct/wanted accuracy.
             question about decima of marketinfo() - MQL4 programming forum 2016.05.18

2. NormalizeDouble does not return a string.
   

I am not calculating a new number; I am simply converting a string to a double. I do understand floating-point numbers and I had nightmares normalizing price with NormalizeDouble (in the beginning), but then read that it's not recommended, so switched to the MathRound() method.

I receive a STRING that I need to convert to a price I can work with. Question is simple, really: Is there a way (YES/NO), based on the code I inserted above, to convert "80.198" to an exact number representation of that string?

Yes.

double value=StringToDouble("80.198")

Buy if you want to print it to 3 digits

DoubleToString(value,3)