I confess that, at first, I tried to round the value directly, but then I remembered that Math.ceil only works for floats, so:

Divide the number by the multiple (5):

value / 5 = X

Since we're rounding up, we'll round it to the next whole number, which is Y.

Now, multiply Y by multiple (5) to find the nearest multiple of 5 that's greater than the "value"

function gradingStudents(grades: number[]): number[] {
	const response = grades.reduce((acc, value, index) => {
		const next = Math.ceil(value / 5) * 5;
		const factor = Math.abs(next - value);
		acc[index] = value;
		if (factor < 3 && value >= 38) {
			acc[index] = next;
		}
		return acc;
	}, [] as number[]);
	return response;
}