How to use SUMIF to add values by unique Reference ID?

I am trying to write a formula that adds cell values by matching the reference ID in a separate column. For example, cells G2 and G3 have the same ID, so the amounts in cell H2 and H3 would be added together, and that total, $21.12, would appear in both I2 and I3.

I've been trying to use SUMIF for this, but have only been successful when specifying the exact reference ID in the formula. I need the formula to automatically match based on any Reference ID. Is there any way to use a SUMIF (or another function altogether) to match strings to calculate values?