You do not specify a year.
If by "Perfect" you mean "Mint condition" and "Uncirculated", a New Zealand 5 cent coin could fetch anything from $1 to $100 (NZD).
A reputable coin dealer will be able to give a more accurate valuation.
NOTE - All New Zealand 5 cent coins are no longer legal tender, but they are redeemable for face value at the Reserve Bank of New Zealand.
It is worth one cent whether it is in perfect condition or not.
The value of any coin would depend on the year and the condition. Most New Zealand decimal coins, unless they are in mint uncirculated condition, would be worth face value only. NOTE - All New Zealand pre-2006 50 cent coins are no longer legal tender, but they are redeemable for face value at the Reserve Bank of New Zealand.
In perfect condition it is worth 25 cents.
All New Zealand pre-2006 10 cent coins are no longer legal tender, but they are redeemable for face value at the Reserve Bank of New Zealand. All New Zealand 10 cent coins from 2006 onwards are still in circulation so, unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they are worth 10 cents in New Zealand.
The first New Zealand 1 cent coin was issued in 1967.
The New Zealand 5 cent coin was withdrawn from circulation in 2006 and is no longer legal tender, although they are redeemable for face value at the Reserve Bank of New Zealand. There were two variants of the 1967 New Zealand 5 cent coin, one with the sea in the background and one without. The coin without the sea in the background might fetch up to $100 NZD if it is an absolute mint condition. The 1971 5 cent coin might fetch up to $20 NZD if it is an absolute mint condition. The 2004 5 cent coin of which there were only 48,000 issued, might fetch up to $135 NZD if it is an absolute mint condition.
A New Zealand 1998 5 cent coin, uncirculated and in absolute mint condition could fetch up to $2 NZD. There were 8 million minted. A reputable coin dealer will be able to give a more accurate valuation. NOTE - All New Zealand 5 cent coins are no longer legal tender, but they are redeemable for face value at the Reserve Bank of New Zealand.
The New Zealand 5 cent coin was withdrawn and demonetised on the 1st of November, 2006. All New Zealand pre-2006 5 cent coins are no longer legal tender, but they are redeemable for face value at the Reserve Bank of New Zealand. Unless they are part of a Proof or uncirculated mint set or are individual Proof or uncirculated coins and in absolute mint condition, they are worth 5 cents.
New Zealand 20 cent coins have never been minted in gold.
A New Zealand 1979 5 cent coin (only issued in a set), uncirculated and in absolute mint condition could fetch up to $8 NZD. There were 41,000 minted. A reputable coin dealer will be able to give a more accurate valuation. NOTE - All New Zealand 5 cent coins are no longer legal tender, but they are redeemable for face value at the Reserve Bank of New Zealand.
A New Zealand 1968 5 cent coin (issued in a set only), uncirculated and in absolute mint condition could fetch up to $4 NZD. There were 75,000 minted. A reputable coin dealer will be able to give a more accurate valuation. NOTE - All New Zealand 5 cent coins are no longer legal tender, but they are redeemable for face value at the Reserve Bank of New Zealand.
A New Zealand 2002 50 cent coin, uncirculated and in absolute mint condition could fetch up to $2 NZD. There were 3 million minted. A reputable coin dealer will be able to give a more accurate valuation. NOTE - All New Zealand pre-2006 50 cent coins are no longer legal tender, but they are redeemable for face value at the Reserve Bank of New Zealand.