Every item (unless specifically stated) can only be purchased with one type of coin. This will then require converting between tiers of coins. Every day, every possible conversion will be either listed or updated. Each conversion will start at 10 and will change by -10 to 10 each update. To convert, you also need to pay a tax. The tax will start at 10% rounded down, and will randomly change, just like the conversions, by -10 to 10 each update. You may only convert up or down 1 level, unless you pay the Multiple Level Conversion Premium Tax (MLCPT). The MLCPT will start at 20% rounded down and will change by -10 to 10 every update. This is useful if the MLCPT is very cheap and therefore is easy to pay.
To convert, you must message an Admin with how much you are converting, up or down, the Taxes or MLCPT, how much the tax is, and the date of conversion.
Because I an horribly uncreative, the coins will be named after the Minecraft Ores and one modded ore.