How change the code in woocommerce for weight cart - woocommerce

Question

Good afternoon, how to change the code so that it works correctly.
The task is to show the weight of the basket and offer, report to the buyer more goods and save on delivery.
Which algorithm I want to implement.
The system summarizes the weight of all products in the basket.
Next, the system should round up to the nearest kg in a big way
and subtract the amount of the basket from this and show it to the client.
An example, like this.
In a 3.05 kg basket, the system and is rounded up to the following = 4
Then 4-3.05 = 0.95 and it displays put and 0.95 and there will be happiness)))
And this is the message that comes out
"The current order weight is 3.05(kg) The delivery calculation is a multiple of a kilogram. You can save on shipping to put the goods weighing another 0.95(kg) and the delivery price will not change
/**
* Output the weight of the shopping cart for the upsale
*/
add_filter( 'woocommerce_before_cart', 'display_total_weight_notice' );
add_filter( 'woocommerce_before_checkout_form', 'display_total_weight_notice' );
function display_total_weight_notice( $message ) {
// ОПРЕДЕЛИТЬ допустимый предел веса
$allowed_weight = 1;
$cart_total_weight = WC()->cart->get_cart_contents_weight();
if( cart_total_weight <= $allowed_weight ) :
wc_print_notice( sprintf(
__( 'Current order weight %s. The calculation of delivery is a multiple of a kilogram. You can save on shipping by putting the goods weighing another %s and the shipping price will not change' ),
'<strong>' . wc_format_weight($cart_total_weight) . '</strong>',
'<strong>' . wc_format_weight($allowed_weight - $cart_total_weight) . '</strong>'
),'notice' );
endif;
}