Rounding Numbers down and up - CRM 8.2

Is there an option, plugin, setting or JavaScript where a number can be round down or up in Dynamics 365 CRM on premise version 8.2 ?

Ideally like to use on the tax fields.

Due to UK and EU VAT regulation rules are

• If the VAT on any transaction comes to less than 0.5 of one penny, it should be rounded down.
• If the VAT comes to 0.5 of one penny or more, it should be rounded up.

Thanks,

PJ