It does not make sense to me to have a five year old "shop" with money she does not have, and especially not with a maxed out cc from Dad.
How about making it a family policy that gifts for each other should be self-made? That they should truly take the recipient into account. It is not the $$ value that is important, but that the giver has really thought about how to please the recipient and that it comes from the heart, especially when you are talking young children.
I agree with many of the earlier posts: Be specific in asking for something that they can DO, individually or together: breakfast in bed was mentioned, it could also be planning/preparing/serving a nice family dinner, for example for New Year's eve? Coupon books are always great, and the daughter can make her own, if she needs Dad's help with the writing, he can do that, but she can cut and decorate and bind together. What could a five year old do?
Plenty! Pick up her room without being asked for a week. Sweep the floor. Take out the trash. Play a board game with mom and dad. go for a walk with mom and dad. or with mom alone. Brush mom's hair when she is tired or stressed out. a back rub.
So many things! It could be chores that she does not really like to do, chores that are normally not hers to do, to spend time with mom, do activities together (one-on-one or as family, or both).
He could also help her with a craft activity, e.g. does she have beads? He can suggest (and help her as needed) to make a necklace for you, or a bracelet. I have some that my sons made for me when they were little with plastic beads and knitting yarn (with no help from an adult), that are near and dear to my heart.
One year I received a box from my son (he was in K5, now that I think of it), beautifully wrapped (alone, by himself). The box was empty, at least it looked empty. He explained that he blew a lot of kisses into the box, so I would always have some, and would always know he loves me, even if he is mad sometimes. How sweet was that? And it cost nothing.
And Dad can make a coupon book too: prepare and serve a romantic dinner for the two of you on a date night (does NOT have to be expensive, it is about the thought put into it, doing the work and going the extra mile to make it look and feel special); massage was mentioned already; time for mom to allow her to do something for herself (go out with friends, or take a leisurely bath, for example) by taking over household and child care duties at a time when he would not normally do it; being available for activities that mom likes and he maybe not so much (walk, play games, do yard work TOGETHER, do cleaning TOGETHER); and there can be multiples of some of those coupons they don't all have to be unique.
Allowing someone to give a gift to you is as important as giving gifts yourself. And teaching kids from early on that gifts should come from the heart, and that is not determined by the price tag alone, is a valuable lesson that will help them be more caring as they grow older and into adult hood.