Given a number, how can I find the nearest two numbers which starts with 1, 2.5 or 5? (10, 25, 50, 100, 250, 500, 1000...endless)

The result should be the nearest nearest higher number, and one below it.

For example: the number 420 should return 250 and 500.
For example: the number 10 should return 10 and 25.

Can use Lodash if it's helpful.

Thanks.