#coding:utf-8
#dictionary 
#弁当の購入　N.SUN 2023/1/1

Bento = {"唐揚げ弁当":450, "日替わり弁当":500,"とんかつ弁当":450,"チキン南蛮弁当":450}
sidemenu = dict(カツ丼=450,ソースカツ丼=450,ホットドック=200,焼きそばパン=250)

mycart ={}

def chooseOpt():
    print('''
          1: 弁当一覧
          2: 弁当を選ぶ
          3: カートを確認
          4: 精算
          5: おわり
          ''')
    
while True: 
    chooseOpt()
       
    opt = input("オプションを選んでください：　")
    if opt in ['1','１']:
        for key in Bento:
            print(key,":",Bento[key],"円")
        for key in sidemenu:
            print(key,":",sidemenu[key],"円")
    elif opt in ['2', '２']:
        name = input("弁当の名前を：　")
        number = int(input("個数を：　"))    
        mycart[name] = number
    elif opt in ['3','３']:
        for key in mycart:
            print(key,":",mycart[key],"個")
    elif opt in ['4','４']:
        total = 0
        for item in mycart:
            if item in Bento:
                total += mycart[item]*Bento[item]
            elif item in sidemenu:
                total += mycart[item]*sidemenu[item]   
        print("総額＝",total,"円")
    elif opt in ['5','５']:
        print("ありがとうございました。") 
        break

            

デモ