50% every 5 years > 10% every year

As I meet more EAs, I'm surprised at the number who donate 10% annually. I share their bias and preference to give now, although I acknowledge there is a somewhat-convincing argument for investing now and giving later. (I've overcome this objection by seeking out donation matching opportunities.) Whatever you reasoning, if you prefer to give now, you really should consider giving a larger amount every few years (up to 50%), instead of giving 10% annually. I'll explain why below.

In the US the standard deduction is $6,500. In my understanding, this is a number the IRS uses to prevent paperwork, trickery, and oversight of deductions. Assuming you make around $70,000 per year and donate 10%, only ~$500 of your donation will be tax exempt. This assumes you had little to no other deductions, which is a reasonable caveat for most of life. 

Have you ever wondered why EAs seem to fall into two groups? Those who give 10% and those who give 50%? I don't believe it's because those who give 50% are 5 times as generous. I believe it's because once you get above $6,500 in deductions + donations, each additional dollar costs only about $.66 to donate. More simply, donating a larger percentage becomes less expensive. 

The full math is pedantic, but I trust you to understand and restate this point: For each dollar you give above $6,500 (minus your other deductions), you will receive a tax refund of approximately 35% (though the exact percentage varies based on your tax bracket). Generally, the more income, the higher your bracket. In my experience, the size of my refund has actually been about 50% of my total donations, though like I said, this will vary based on your other deductions and gross income.

After receiving your first large refund check, you'll want to plan ahead--because money now is better than money later. If you increase your exemptions on your W4, your refund will be smaller, but you'll get to keep more of your paycheck, and your net income after taxes remains the same. There is a handy tool on the W-4 to determine how many exemptions you should claim based on your expected donations. For 50% of income, I remember the exemptions being ~10.