Valid & Invalid transactions

Q: I would like to know if buying a box with the contents being unknown permissible or not. Example there are 5 closed boxes you cannot open before buying but the estimated value is R100 each. It can be worth more, it can be less. If the estimated value is R100 and it's on an auction platform, the bid can land upto R800 example or can cost you R100. 

Is this permissible to buy? 

Please note that each box will have something and none will be empty but it can be something with very low value. 

Q: Is it permissible to renegotiate a business deal that one had previously agreed to but had not considered the consequences thoroughly?

Q: I wanted to find out a fatwa regarding weights and measures in my business. 

We are steel traders. We buy steel a certain thickness say 0.2mm but the factories that produce it can’t get the exact thickness due to the production process. So the thickness varies from 0.195 to 0.205mm, sometimes more sometimes less. 

What is the ruling on this because we sell the product as 0.2mm. We sell as per the thickness that we order. We don’t order a lower thickness and sell as a higher thickness. This is purely a production tolerance level as the machines can never get it exact.

Q: Is it permissible to bypass an estate agent in purchasing a property? 

Example, I see a property for sale on their website/see their board outside the property. I then go directly to the seller and do a private deal with them, to avoid getting the estate agent involved and to avoid paying them commission. Is this permissible?

Q: In some businesses it is common practice to special order an item for a customer, when it is not in stock, by taking a non-refundable deposit, e.g., 25% or 50%. At times the following situations arise after the item is purchased from the supplier and it arrives: 

1. The customer pays the balance and the sale is concluded. 

2. The customer changes their mind and then wants a refund, which is refused because the item was specially ordered. 

Is it permissible to conduct business in this manner?

Q: I have seen previous questions, about whether purchasing extended warranties which are a separate line item at the time of purchasing a product, are haraam. 

Please advise if it is permissible to sell the same item, at different price points but the higher price point has a longer warranty? The warranty is not a separate line item.

Q: Some stores mark products at a certain price but round off the amount. For example, the item is marked at R12.99 or R12.95, but they then round off the amount and sell the product at R13. There's no question of change. Is this permissible?