Traditional sales model

Here is my experience having been in retail and manufacturing ends of products then ideally:
widget game costs $10 to make, manufacturer/publisher Calculates MSRP under following conditions.
manufacturer sells to distributor for $20
Distributor to retailer for $30 (50% markup)
retailer to consumer for $45 (50% markup)
So MSRP is at least $45.00

Unless orders are in sufficient quantities to justify free shipping all shipping costs are paid by the receiving entity. (distributor or retailer, consumer if it is mail order)

I have seen this formula in use may times.Remember the profit made pays for staff, facilities, and any other costs of doing business at each level.

Although the retailer has the highest markup they also have the greatest risk and have to be willing to accept sometimes putting an item on sale to compete or get rid of "dead" stock.

If you sell direct to retailer then the MSRP could be less but you still need to keep the profit in it. Otherwise why should a retailer tie up their hard earned capital in your game.

you got it. I've worked and managed various retail stores along with product design for a specialty tool company and these are the desired markups.
As to shipping that is why you try to order as much as possible, it is cheaper per item to ship a pallet of goods rather than 1 or 2 items in a box.

The cost of shipping is one of the largest obstacles to the small publisher, and a contributing factor to the existing three-tier distribution model.

Unless special arrangements are made, the receiving entity expects to pay the cost of shipping goods which they have purchased. The distributor model allows retailers to achieve an economy of scale and save money on shipping costs.

Shipping tends to have a high initial fixed cost and a low marginal cost. For example: ABC Shipping charges $100 to ship a single pallet weighing up to 100 pounds, plus $1 for every additional 10 pounds to a maximum of 300 pounds. The retailer then prefers to ship a single heavy pallet from a distributor than to ship multiple light pallets from several publishers. It just costs less.

Because a retailer will seldom order more than a few units of any given product at a time, it is difficult to achieve an economy of scale when products are divided among several publishers. They are unable to create a heavy pallet. By aggregating products through a distributor, a retailer can purchase from multiple publishers and still achieve an economy of scale.

Distributors can also achieve an economy of scale by placing large orders from a publisher and distributing those units across multiple retailers in combination with products from other publishers. Fulfillment services like those provided by Game Salute provide distributors with large catalogs from which to purchase, allowing them to achieve that economy of scale with shipping.

Retailers also benefit by dealing with a single supplier, greatly streamlining the time and effort spent in tracking, invoicing, and receiving.

I think the discussion of margins is fairly well covered. I would hesitate to say the numbers are "industry standard" (I've never experienced such a thing) but I'm confident to say they are a good "industry average".