Deep learning (and indeed any kind of machine learning) is really not necessary here. I wrote a very simple baseline that estimates the total gross amount as the biggest numerical value present (favouring ones that begin with a dollar sign and/or occur more than once). This achieves 93% accuracy (code is here https://gist.github.com/rlmacsween/166b7c1c1b0c5f466a0fe9b46...) in comparison to the 90% for the deep learning model.