WoodMart theme - sale label in percentage w/decimals

function woodmart_product_label() {
   global $product;
   $output = array();
   $product_attributes = woodmart_get_product_attributes_label();
   $percentage_label = woodmart_get_opt( 'percentage_label' );
   if ( $product->is_on_sale() ) {
      $percentage = '';
      if ( $product->get_type() == 'variable' && $percentage_label ) {
         $available_variations = $product->get_variation_prices();
         $max_percentage = 0;
         foreach( $available_variations['regular_price'] as $key => $regular_price ) {
            $sale_price = $available_variations['sale_price'][$key];
            if ( $sale_price < $regular_price ) {
               $percentage = round( ( ( $regular_price - $sale_price ) / $regular_price ) * 100 );
               if ( $percentage > $max_percentage ) {
                  $max_percentage = $percentage;
               }
            }
         }
         $percentage = $max_percentage;
      } elseif ( ( $product->get_type() == 'simple' || $product->get_type() == 'external' ) && $percentage_label ) {
         $percentage = round( ( ( $product->get_regular_price() - $product->get_sale_price() ) / $product->get_regular_price() ) * 100, 2 );
      }
      if ( $percentage ) {
         $output[] = '<span class="onsale product-label">-' . $percentage . '%' . '</span>';
      }else{
         $output[] = '<span class="onsale product-label">' . esc_html__( 'Sale', 'woodmart' ) . '</span>';
      }
   }
   if( !$product->is_in_stock() ){
      $output[] = '<span class="out-of-stock product-label">' . esc_html__( 'Sold out', 'woodmart' ) . '</span>';
   }
   if ( $product->is_featured() && woodmart_get_opt( 'hot_label' ) ) {
      $output[] = '<span class="featured product-label">' . esc_html__( 'Hot', 'woodmart' ) . '</span>';
   }
   if ( get_post_meta( get_the_ID(), '_woodmart_new_label', true ) && woodmart_get_opt( 'new_label' ) ) {
      $output[] = '<span class="new product-label">' . esc_html__( 'New', 'woodmart' ) . '</span>';
   }
   if ( $product_attributes ) {
      foreach ( $product_attributes as $attribute ) {
         $output[] = $attribute;
      }
   }
   if ( $output ) {
      echo '<div class="product-labels labels-' . woodmart_get_opt( 'label_shape' ) . '">' . implode( '', $output ) . '</div>';
   }
}