Issue with too many Decimal Places

I am currently building my websites designer, however no matter what i try i cant get these decimal places to stop showing.

When customising a product it shows the price without the extra decimal places, but as soons as the price goes over £70 it adds loads of 9's on the end?

See screenshot here

https://alteredlaboratories.com/product/test/

Any ideas how to fix?

Thanks!