Calculated prices need Math.Round(x + y, Symbol.Digits) when using <= to prevent .9999999999

I've recently resolved an issue in my code where I was using a <= operator to check the prices of a bar with a calculated price.

While I was rounding the initial values using Symbol.Digits, when I added them together, the double they were written to, had .99999999 and so prevented the = part of the <= operator from being true. >= seems to work fine.

I was not expecting this and am now going through my code looking for <= and making sure any calculated price is rounded.

It would take a fair bit of work to write an example.

While cTrader showed the values rounded using a print statement, the = part of the operator wasn't being triggered - after debugging in visual studio I could see the calculated value had the 999999999 at the end.

Any idea why adding two prices such as 1500.05 + 375.55 would result in 1875.599999999 ?