custom_get_increase_bid_value

add_filter( 'woocommerce_simple_auctions_get_increase_bid_value', 'custom_get_increase_bid_value', 10 , 2 );

function custom_get_increase_bid_value( $auction_bid_increment, $product){

    $bid_value = $product->get_curent_bid();

    switch ($bid_value) {
        case $bid_value <= 25:
            $auction_bid_increment = 2;
            break;
        case ( $bid_value > 25 && $bid_value <= 80 ):
            $auction_bid_increment = 5;
            break;
        case ( $bid_value > 80 && $bid_value <= 230 ):
            $auction_bid_increment = 10;
            break;
        case ( $bid_value > 230 && $bid_value <= 750 ):
            $auction_bid_increment = 20;
            break;
        case ( $bid_value > 750 && $bid_value <= 2000 ):
            $auction_bid_increment = 40;
            break;
        case ( $bid_value > 20000 && $bid_value <= 6000 ):
            $auction_bid_increment = 80;
            break;
        case ( $bid_value > 6000 && $bid_value <= 20000 ):
            $auction_bid_increment = 200;
        break;
        case ( $bid_value > 20000 && $bid_value <= 50000 ):
            $auction_bid_increment = 500;
        break;
        case ( $bid_value > 50000 ):
            $auction_bid_increment = 10000;
            break;
    }

    return $auction_bid_increment;

}