Absolutely, the $50 has caught on in New Zealand as its placed in ATM machines and people are facing up to using them. But $100s, thats casino and drug mule/cash laundering territory still. Cooks its mainly $20 and down as they are a bit poorer there, $50 is a lot of money and not useful for village shop purchases.
Heres their coins over time.

These are the current coins of the 2015 era. The cents coins are shrunk down stainless steel ones, in the style of NZ and recycle the 1970s designs. The dollar also shows Tangaroa, god of the sea. The $2 shows a mortar and pestle. The $5 shows a navigational waka with stars. This is a large coin. The dollars are easy to find, cents are much less easy.
These are the 1987 to 2015 coins, and feature old cupronickel 5 to 50 cents. The 50 cents (tene) had a design change in 1987. The dollar was shrunk in size around 1990 and the $2 was released in 1987, so was the $5. The older coin has a conch shell and these coins were all demonitised in 2015. The 5, 10, 20 tene are the same designs as earlier coins, but minted in Stainless Steel rather than Cupronickel as it was lighter and cheaper. This was similar to Fiji which also switched to steel in 1990 and Papua New Guinea around the same time. The 50 tene was also a steel coin now too.

These are the original 1972 to 1987 coins, all bronze and cupronickel, the original 1c and 2c were phased out around 1990, all were cupronickel. The dollars were large crown sized coins and were used a lot, ironically with $3 notes showing another half naked goddess riding on a whale (Tangaroa is anatomically correct!). The 50 cent coin showed a bonito and this design was recycled for the modern 50c.

Obverses for pre 1987 coins and post 2010 coins, the 1987 - 2009 coins showed the Maklouf effigy (I don't have a photo of one).
Before 1972, Cook Islands used New Zealand coins, a commemorative dollar from 1970 was only issued in New Zealand - but this coin likely led to the idea of the Cooks getting their own coinage.

This was one of the commemorative “large dollars” issued and thus was sold as a souvenir only - although legal tender it did not circulate either here or in the Cook Islands (Mainly as they were sold for about $4 each then!).
Hope this clears up the Cook Islands coin controversy!
I love coins. Especially silver, gold and anything really old.
Member of the Royal Numismatic Society of New Zealand and the Auckland Numismatic Society