Trouble with Math method

I am working up a utility that will convert numbers
with decimal fractions to minutes and seconds; as in
angular measurements and time (hour) measurements

Since the Math.round method will not allow specification of places to round to
I have developed an approach for that. But it is depending on the use of
Math.pow(10, [specified places])

The places can be positive for powers and negative for roots to shift the decimal
point spec places to the right (+) or to the left (-)

However, I am getting very small values in the result of Math.pow:

In the code below I am trying to round second value to .1, so I get
a value like x.y.

This code represents the hoops I have to jump through to get the
intended result: 4.564983 -> 4 degrees 33 min 53.9 sec

The problem is marked <<<<****;

Is there a better builtin than Math.pow?

For info; in the code you will see sec = sec - sec%1
That will remove the decimal fraction from the number.
sec%1 is save in a separate variable.
4.5%1 == 0.5
4.5 - 4.5%1 == 4

I have not been able to get 4.565%0.01
to produce 0.065, for example.

Thanks for time and attention:
JK