To give my two pennies worth is to give my opinion or point of view on something. It can be a humble way of offering to share your thoughts, by pricing it as low as two pence.
I would like to put in my two pennies worth, before we finish the meeting.British English
Contrary to its meaning, the idiom’s origin could be the ironic response to an uninvited opinion, as in – “I said a penny for your thoughts, but I got two pennies worth!”
Two cents or two bits’ worth is also used, maybe denoting the first bet to enter the table for a game of poker. This modern origin of the idiom, could be just a speculation but seems convincing to me. That’s just my two pennies worth 😉
If the changes are going to affect him, he will want to put his two cents in.American usage
Another theory behind the origin of the idiom could be the “Twopenny Post“. The only evidence based origin to this phrase however, is an article by Allene Sumner, headed “Two cents’ worth”, in print, from the Olean Evening Times of March 1926.