Ruby Fundamentals II. This Cash register takes multiple items, returns the total, then sums up multiple tendered amounts till the total is met and returns the change.

Cash Register Multiple Input

all_prices = []

price = ""

until price == "done" do

	puts "What is the sale price?"
	price = gets.chomp

	if !price.match(/\A\d+(\.\d+)?\z/)
		puts "Please put in a real price!"
	else
		all_prices << price.to_f
	end
end

subtotal = all_prices.inject(0) {|sum, i| sum + i}

puts "Here are your item prices: \n"

all_prices.each {|x| puts "$#{sprintf('%.2f', (x))}"}

puts "The total amount due is $#{sprintf('%.2f', (subtotal))}"

amount_tendered = 0
total_tendered = 0

until total_tendered >= subtotal do
	puts "What is the amount tendered?"
	amount_tendered = gets.chomp

	if !amount_tendered.match(/\A\d+(\.\d+)?\z/)
		puts "That's not real money! Try again!"
	else
		total_tendered += amount_tendered.to_f
	end
	puts "You've given me $#{sprintf('%.2f', (total_tendered))} so far! \n Give me $#{sprintf('%.2f', (subtotal - total_tendered))} more!" unless subtotal - total_tendered <= 0
end

puts "===Thank You!===", "The total change due is $#{sprintf('%.2f', (total_tendered.to_f - subtotal))}", 
		 "", Time.now.strftime("%m/%d/%Y %I:%M%p" ) , "================" 

this is a good - I would start to pull out methods as a next step. So for instance these:

    if !price.match(/\A\d+(\.\d+)?\z/)
        puts "Please put in a real price!"
    else
        all_prices << price.to_f
    end

    if !amount_tendered.match(/\A\d+(\.\d+)?\z/)
        puts "That's not real money! Try again!"
    else
        total_tendered += amount_tendered.to_f
    end

could be changed to:

   def not_real_money?(input)
      !input.match(/\A\d+(\.\d+)?\z/)
   end

   if not_real_money?(amount_tendered)
    puts "That's not real money! Try again!"
   else
       total_tendered += amount_tendered.to_f
   end