Floating-point rounding errors when serializing amounts

[saltire]

The numberFormat function in /src/Gateways/RealexConnector.ts doesn't always parse floats correctly, and needs to do some rounding.

For example:
numberFormat(2.28) returns '227.99999999999997'
numberFormat(19.76) returns '1976.0000000000002'

[foodciti]

@saltire HAVE YOU RESOLVED THIS ISSUE. I STUCKED IN THIS