Hi @Osman-Hajr, this is really great work, I think you have a good understanding of the material here. The only note I had was for your calculateSalesTax function below:

Careful not to have redundant code, e.g. for calculating sales tax you have used the priceUnit parameter twice and multiplied it by 1 which is unnecessary:

function calculateSalesTax(priceUnit) {
	let taxedPrice = priceUnit + (priceUnit * 1) / 5;
	return taxedPrice;
}

Instead, you could write it like:

function calculateSalesTax(priceUnit) {
	let taxedPrice = priceUnit * (1 + 1 / 5);
	return taxedPrice;
}

Which will do the same thing with less repetition.

Like I said, this is great work overall!