Tracking monies.

[SenorZ]

I'm a new mentor to my team (2nd year team) because I'm new to the school. At my old school we had an FRC team, and I pretty much handled the financial stuff, tracked deposits and expenditures, collected receipts, and submitted for reimbursements from our account.
At my new school we have an ASB account (which we don't really use much) and an Ed Foundation account, a student financial officer (who's learning ropes and graduating this year), and a parent financial advisor (who hasn't been doing a lot of advising). We have multiple mentors making purchases, including myself, and we're not doing the best of jobs keeping track of everything... mainly because everyone is working hard on the robot and their schooling/jobs.

What do most teams use to keep track of all the expenses? We have a (in my opinion) convoluted spreadsheet system that I'm in the process of rebuilding from the ground up. Is there a preferred software? website? ledger book?

I'm looking forward at post-build season stuff to do with students, and when they elect a new board of directors I want to work with the new financial officer on a system that will work without hassel. Any advice is appreciated.