" Do I have to report each reward I get for mining the coin?"
No, you do not "report" each reward in your income tax return, but on your own you do need to keep track of each reward and translate that reward into US Dollars when received. You will report the sum of all your rewards for the year as "Revenue" on Schedule C where independent contractor/sole proprietor income is reported. You should be able to use a source such as http://coinmarketcap.com/ to do the conversion from cryptocurrency to US Dollars.
"Also, I will not be converting any of these coins back to USD this year. Will I still need to claim it?"
Actually converting the coin to USD is not necessary to make the act of mining reportable.
"I am not sure how any of the taxes work for the cryptocurrencies. Is
there a rule of thumb for how much I should set aside for the taxes on
these coins? 1/3? More/less? "
Your profits from mining, if any, will be subject to taxes at your "ordinary" income tax rate and that depends on your total taxable income from all sources. This profit will also be subject to Self Employment taxes at roughly a 15% tax rate. So it's impossible for anybody here to really provide a percentage amount, though I'd think a 33% would be more than adequate.
Any conversion of the coin to USD and/or alternative coin would also be subject to short term or long term capital gains rate, depending on how long you held the original coin. (Long term > 1 year.) So you need to keep track of your USD value for each reward - that's your "basis" in the coin - and figure gain or loss based on the actual conversion rate to USD at the time of the conversion.
Tom Young
