The conversion is pretty easy. Since there's 100,000,000 sats in one Bitcoin, the calculation is

100,000,000 / [Current Price] = $1 worth of sats

For instance, the price as of writing this is about $29,820

100,000,000 / $29,820 = 3,353 sats

Now, bear in mind that people are often less willing to give up sats, and you are benefitting from immediate, final settlement when they do pay in sats, so you may want to do a bit of a discount for those who pay in sats rather than dollars.