PPS Plus Software interview questions

After applying online. Phone interview first. Next was initial in-person interview with director. Third was in-person interview with managers. After this an offer was made. Offered base salary comparable to new floor nurse at local hospital plus a percentage of monthly invoices. Compared to other similar companies, both the salary and commission are relatively low. Not sure how they maintain employees beyond training in this department when you can get trained and certified and then leave for 50% higher salary in addition to higher commission on charts reviewed.