wallet: dust limit calculation should round up (not down)
wallet: dust limit calculation should round up (not down)

related to prev commit

closes #6035

pooler/electrum-ltc,vialectrum/vialectrum,vialectrum/vialectrum,wakiyamap/electrum-mona,spesmilo/electrum,pooler/electrum-ltc,spesmilo/electrum,vialectrum/vialectrum,spesmilo/electrum,wakiyamap/electrum-mona,wakiyamap/electrum-mona,wakiyamap/electrum-mona,pooler/electrum-ltc,spesmilo/electrum,pooler/electrum-ltc