more or less; give or take; roughly
Used to indicate that a small difference doesn't matter; the overall situation is about the same regardless of slight increases or decreases. Often implies a rough estimate or that the exact number isn't important.
Whether it increases or decreases a bit, there will be about 30 participants.
値段は増えても減っても、今とあまり変わらないと思う。
Give or take a little, I think the price won't change much from now.
A set phrase combining the conditional forms of 増える (to increase) and 減る (to decrease) with the particle も, literally 'even if it increases, even if it decreases'.