Paste the following in functions.php:

/* round cart total to nearest 0.05 cent */
add_filter( 'woocommerce_calculated_total', 'custom_calculated_total' );
function custom_calculated_total( $total ) {
$total = round($total / 0.05) * 0.05;
return ($total);
}

Sources: https://stackoverflow.com/questions/50241524/round-up-cart-total-woocommerce/50242494, http://martinpennock.com/blog/round-nearest-5-cents-nickel-php/, https://www.php.net/manual/en/function.ceil.php