The previous Advanced Tip Calculator is simply an extracted version from the Advanced Financial Calculator. It doesn’t have a good usability. So I redesigned the tip calculator over the weekend and release it as donationware. There are both free-ads-support version “Tip Calculator Donation Free” and paid version “Tip Calculator Donation”. The ads revenue and sales revenue from both  apps will be COMPLETELY donated to some non-profit/charity organizations to help people in need (such as fighting with AIDS or cancer, post-catastrophe reliefs, helping people in poor countries). And I will post receipts with the amount when it happens.