Encourages is the operative word here.
Tithing is not specified in the NT, mainly because it was the law, and in the Kingdom, 100% of what we possess belongs to God.
Tithing in modern churches has become a tax, and like most tax, more of it is spent in administrating the tax yield than in using it for the purpose it was intended, in the NT we are charged with caring for the homeless, dispossessed, widow and orphans, prisoners and all others in need.
If believers follow those instructions, it may well cost them more than 10% that the Levite priests were entitled to, or even the 22% which was the full tithe when you took into account all the sections of it, but even if it does not reach those levels of expenditure, the blessing is in the doing, not the cost.
Prayers are not being answered mainly because we have forgotten how to pray for what God wants, and have taken to petitioning for what WE want.
In countless prayer meetings I have attended I have heard soulish prayer and often needed to cite scripture to alleviate the almost witchcraft element that can start spouting out when groups get together.
Prayer is a private and personal aspect of our walk with God, corporate prayer is not seen in scripture.
A solemn assembly being called is, private prayer and fasting is, but prayer groups whipping up emotional prayer requests which may or may not fall in line with Gods will as demonstrated in scripture is not.
Sickness, disease, death, and debt are by-products of not trusting God to guide you in your life. Unfortunately faith does not always equate to trust, and without trust, we turn to other options, which will normally result in one of the above.