Javascript - 从价格含增值税中保存价格不含增值税时出现的圆形问题

Question

In the backend (Node.js) I save my prices in cents (*100) and always excluding VAT.
However, on the frontend we would like the user to be able to define their prices including VAT.

So what we do is as follows:
Price incl VAT: 10,00
Formula to incl VAT: (10*100)/1.21 which gives 826.4462809917355 Math.round it to: 826 The 826 is the price excl VAT which we save in the database.
But when we add the VAT (21%) to it, then it becomes this:

(826/100)*1.21

Which will become 999.4599999999999 .
Math.round makes 999 of it.
So when our users filling in 10,00 as price incl VAT. It will end up being 9,99

Answer 1

The solution I went with is to increase the multiplier (100) to 100000.
Haven't had any issues with it since. Probably not a 100% solution, as I suppose this only reduces the change of issues.