So, how is this sentence related to penny "Łichííʼ" and fifty "Ashdlaʼdiin"?
Łichíí', łitso, dootłizhii etc.. represent the coins or the bills themselves, literally it means the red, the yellow, the blue.. Béeso and Béeso yázhí are used to actually count dollars and cents. Yáál is another unit worth 1/8 dollar. So dį́į́ʼ yáál is a 1/2-dollar. Note that 4 is dį́į́ʼ, not díí as erroneously repeated in other lessons.
Sounds like the yáál is the colonial-era bit, which was the same as the Spanish real. Two bits, four bits, six bits, a dollar.
Yáʼátʼhéé! The word for "fifty" cannot be used here, because "yáál" means "one eighth". So:
"fifty cents" = "dį́į́ʼ" (4) × (⅛) × dollar = ½ × dollar = 0.50 $ (dollar)
I hope it helps. :)