I came across a site recently (ebay I think) that priced in 10cm increments. Very clearly too cheap to be a metre and easy to multiply up.
Bonus: if you want 1.2m or 1.4m you can have it.
It is compulsory to price items such as food etc in £/kg or by unit price to avoid confusion for the consumer. It seems vendors are sidestepping in the field of fabric and calling a half meter a unit where the expected unit should, or would be expected to be, a full meter.
It's a psychological thing, as is pricing everything £xx.99.
Some might say sneaky.