They have so little value that most shops will not take them and banks charge a handling fee for accepting them.
But the 10, 20 and 50 cent coins lying round in jars, bowls and moneyboxes in Hong Kong homes could add up to as much as HK$100 million, according to one estimate.
This has emerged from a survey by the Democratic Alliance for the Betterment and Progress of Hong Kong in which 70 per cent of respondents said sellers and service providers had refused to accept the coins from them.
'Many stalls at the wet market will not accept small coins,' said retiree Tsui Juen-tai, 73. 'Sometimes we even get scolded by stall owners for trying to use them.'
People said that as it was difficult to use the coins, they stored them up, and based on the response the DAB estimates there could be HK$50 million to HK$100 million worth of coins lying unused.
More than 70 per cent of the 1,030 respondents interviewed in the survey last month - half of them aged over 50 - said they stored the coins.
'It is unacceptable that shops and public transport reject even a small number of small coins,' said DAB lawmaker Chan Kam-lam, who oversaw the survey.
'This is caused by the fact that the law does not regulate such actions.'
The Coinage Ordinance says coins of denominations of less than HK$1 can only be used in amounts not exceeding HK$2 but it does not require businesses to accept them.
Another reason that peple store the coins is that banks charge a fee of about 5 per cent to handle them, with 91 per cent of the respondents saying they had never deposited or changed coins and 63 per cent saying the charge was irrational.
'We urge banks to cancel such charges because they have the responsibility to change coins. This will also make shops more willing to receive coins,' Chan said.
Tsui said that although shop owners rejected small coins, they gave them in change.
'It's not fair. I have two money boxes filled with coins since I cannot find a way to use them,' she said.
The number of 10, 20 and 50 cents coins in use has fallen from 3.5 billion in 2001 to 3.2 billion last year, according to the DAB's report.
The Hong Kong Monetary Authority stopped putting new coins into circulation in 1998 because the number in use was considered sufficient.
The Bank of China charges HK$1 for every HK$20 of 10 or 20 cent coins, with a minimum charge of HK$50. HSBC charges HK$2 for every HK$20 of 10 cent coins and HK$2 for every HK$50 of 20 cent coins.