No @FarmerJoe, for Sells, the closing price has to be equal or higher than the price you have nominated. You are nominating the minimum you are prepared to accept when placing a sell, so if the stock closes lower than that, the sale will not go through.
This is the opposite of buys where you are nominating the maximum you are prepared to pay, so if the stock closes higher than your nominated price, the buy trade will not go through.
There are other rules around liquidity as well. The stock must NOT be suspended from trading at the end of the trading day, and the same number of shares you are wanting to buy or sell - or a greater number of shares - has to have changed hands on that day on the ASX (i.e. in the real world).
For instance, if you are trying to sell 100,000 ABC @ 12 cents each and buy 20,000 XYZ at $1.01 each, and the volume traded for ABC during that day was only 80,000, either none of your sell order - or only part of it - will go through, but only if ABC closes at 12c or higher. Even though you would have nominated 12c, if the liquidity is fine and ABC closes at 14c, your sell trade will go through at 14c, not 12. If XYZ goes into a trading halt at 3pm and remains in a trading halt at close of trade, no buys or sells will be processed by Strawman for XYZ that afternoon/evening. They have to be actively trading at the close for any trades to go through. If XYZ was trading, and at least 20,000 shares were traded during the day on the ASX, your Strawman.com buy order for 20,000 XYZ would go through if XYZ closes at $1.01 or lower. If they close at 99c, your buy price on Strawman.com would be 99c, not $1.01.
However, behind ALL of that is the cash rule - BUYS only go through if there is sufficient virtual cash available in your Strawman.com account to cover the trade. The system will attempt to process all sells first, if they qualify (are within the rules, as outlined above), then will process the buys in the order that they were placed, until there isn't enough cash left to continue. You might think there should ALWAYS be enough cash, but that is not the case. In the example above, when you place your sell order for 100,000 ABC at 12c each, the system automatically increases your available cash by $12,000. In reality, you don't have that cash, but if that sell order goes through at the end of the day you will have, so the system makes that adjustment to your cash balance immediately to allow you to load up one or more buy orders. However, if one or more of your sell orders do NOT go through - for any one of the reasons I've listed above - then obviously that affects the cash available to process any buy orders you have placed, and often results in one or more of those buy orders not going through due to insufficent cash to cover the trade. If there is not enough cash to cover the entire trade, then none of that trade will be processed, so it's all or nothing with each trade. The only time you might see only part of an order go through would be due to the liquidity rule as detailed above (not enough shares traded on the real market) - but I have never actually seen that occur myself. With all of my trades - they have either gone through or they haven't. All or nothing. I have never had a part-trade executed with the other part left in the market. I had heard that might happen (when there is insufficent liquidity in the real market) but I haven't seen it myself. I have had part trades occur PLENTY of times in real life, but not here on Strawman.com.
Hope that helps.
P.S. Didn't realise Strawman had already answered your query - sorry!