Li-Ion Battery Charging using current controller
Your method is correct, but your description of the CV part of it is somewhat unusual.  CC uses constant I - how you achieve it is essentially irrelevant. CV mode uses constant V, how you achieve it is essentially irrelevant (BUT do NOT exceed V max (usually 4.2V) on the PWM peaks!).  

You may implement CV control to maintain a constant voltage by controlling buck PWM duty cycle and you can regard that as controlling current if you wish -  as long as the voltage is contant. ie if you wanted yoiu could have decsribed the CC part of the cycle as voltage control with voltage being altered to produce the desired current. That's a potentially [ :-) ] valid viewpoint but ideally you should focus on what your algorithm is doing - not the underlying mechanaism.

So - during CC mode you maintain constant current - the battery :does not care" how you do this. During CV mode you maintain the voltage - the battery again 'does not care' how you do this. 

Reducing CC to C/10 (0.1 of CC rate) is reasonably aggressive and will give you a very well charged cell but a substantial reduction in cell cycle-life. If you do not need every last mAh of storage capacity it is better to charge to say C/4 or even C/2 rate. Capacity per cycle reduces by maybe 5% to 10% (maybe less) but cycle life will improve usefully.