Why am I not able to sell all of my coins of a particular cryptocurrency at once on Binance?

I am new to crypto and was checking all the features of Binance. So I bought minimum amount of XRP just to see how it all works. I bought $10.2 of XRP at $1.2936 which gave me 7.87 XRP.

Now when I try to sell it at limit order, it only allows me to sell a whole number amt of XRP. So I can only sell 7 XRP at once. I should get my $10.2 back when XRP reaches $1.31 but since I can only sell 7 XRP, my break even even point has gone up by 11% to $1.457.

Why is this so? Does this happen with all coins that only whole number amount of coin is allowed to be sold? In this case, how do I sell all of my XRP at once?

Also, in my order history, it says 100% filled and the filled/amount row shows 7/8. Why is it not showing 7.8/8?

Someone help me understand all this.

EDIT: Am not using lite version of Binance. Here's a screenshot of the sell screen. While selling, it's not letting me input decimal number manually and when I tap on 100%, it only takes 7 XRP as the sell order instead of 7.8