I'm working on Law of Sines problems and the text seems wholly inconsistent in the way it rounds answers and when it rounds them.

For example, for $sin(B)=0.3674$ it gives $B=21.6^\circ$(Note 3 significant digits with one decimal)

For $c=\dfrac{8}{sin(36^\circ)}(sin(122.4^\circ))$ it gives $c=11.49cm$(Note 4 significant digits with 2 decimals)

I don't have any problem finding and understanding the rules of rounding and significant figures for adding, subtracting, multiplying and dividing. But I haven't been able to find any published rules on the likes of trigonometric and logarithmic functions - especially inverse functions. Does anyone know where I could find any such rules?