fix deposit order fee calc

spec/services/build_deposit_order_spec.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+require "rails_helper"
+
+RSpec.describe(BuildDepositOrder, type: :service) do
+  describe "#build" do
+    it "returns DepositOrder" do
+      deposit_order = described_class.new(paid_amount_cents: 1000, user_id: 1).build
+
+      expect(deposit_order.paid_amount_cents).to(eq(1000))
+      expect(deposit_order.received_amount_cents).to(eq(950))
+    end
+  end
+end