Forcing decimal places dependant on variable

Hi all,

I have a spreadsheet where I add a % and a total mass, and the sheet generates a weight for that %. The issue arrises when I weigh it out using different methods. I want to specify to be accurate and use 2 decimal places for small weights, or use none for large weights.

I'm happy to have a drop menu to select the level of accuracy, but when i say 5% of 20kg I get 1kg. If I ROUND(A1,2) (for high accuracy) I get 1.00kg, which is great.

I then want to use 1.00 in a concatenate, but it always reverts to 1

tl;dr: What I need is a way of treating a number generated with no decimal places as one with either 0, 1 or 2 decimal places for use in a subsequent concatenate

I'm sorry if this is not sufficiently clear. The book that I am working with has a lot going on around this issue, but I could write a sheet isolating this issue if it is required for clarity