I have a problem that I'm positive someone here can help me with. I've searched all over the internet (till i got a headache) Some get close and I'm apparently not smart enough to take it the rest of the way by myself.

Here's the skinny.

Our vacation year is from May 1st to April 30th. Each employees vacation entitlement is determined on May 1st of each reference year. Employees who have a start date between May 2nd and April 30th accrue 1 day for each month of continuous service to a maximum of 10 days paid time off.

Vacation accrual is a follows for full years of service as of May 1st.

1 year - 10 days
4 years - 15 days
10 years - 20 days
18 years - 25 days

What are your ideas for the best way to do this?