I'll be going through a lot of $5 bills between SAC and WAS starting on Saturday but I would be tipping at restaurants and hotels if not traveling by rain. I have "stop at bank" on my to-do list Friday to stock up with change just for this purpose.
If you are stopping by the bank anyway, here is a suggestion: get your tip money in $2 bills. There are four reasons to do this:
1) A lot of people appreciate getting a 2, because they consider them lucky or whatever, so it is just a nice thing to do;
2) It helps them remember you, so if you tip with a stack of twos at the first meal, they will remember you at the remaining meals (if you are eating in the Diner);
3) It helps make you a slightly bigger tipper, because you round up to an even number of dollars, instead of the next dollar, and being a big tipper is good for the tipper (karma-wise if in no other way) and tippee;
4) Off of Amtrak, it encourages you to tip in cash instead of with a card, which is all the same for you but generally advantageous for the person serving you.
Just a thought. I always have a stack of twos in my wallet just for tipping, on or off of Amtrak.
Happy travels,
Ainamkartma