Suggestions on a Petty Cash table design

I was trying to come up with a setup for a Petty Cash table. The things it
must do the following:

Date Money spent
Where it was spent
What is was spent for
What the item is used for (Office supplies, maintenance, etc.)
How much
Has it been reimbursed 'possibly this field won't be necessary as if the
When had a date it would have been.
When it was reimbursed

Now here is what has me thrown, how to keep track of starting amount and a
running amount in the kitty. For example if we start with say $500 and spend
$100 on several items I will need to know how much is left in petty cash at
that time as well as any previously not reimbursed. Right now we are doing
this in excel but would like to bring it into a single access table for ease
of reporting on it.

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Thanks

Joe Cilinceon