How to round up values in Elasticsearch query?

I am trying to set up an automated Kibana alert that takes in data from a defined extraction query. I get all the information I want, however, the response query returns values without rounding them up (up to 12 decimal points). Where in the extraction query and what do I specify to round this value up?

{
    "size": 0,
    "query": {
        "bool": {
            "filter": [
                {
                    "match_all": {
                        "boost": 1
                    }
                },
                {
                    "range": {
                        "@timestamp": {
                            "from": "{{period_end}}||-24h",
                            "to": "{{period_end}}",
                            "include_lower": true,
                            "include_upper": true,
                            "format": "epoch_millis",
                            "boost": 1
                        }
                    }
                }
            ],
            "adjust_pure_negative": true,
            "boost": 1
        }
    },
    "_source": {
        "includes": [],
        "excludes": []
    },
    "stored_fields": "*",
    "docvalue_fields": [
        {
            "field": "@timestamp",
            "format": "date_time"
        },
        {
            "field": "timestamp",
            "format": "date_time"
        }
    ],
    "script_fields": {},
    "aggregations": {
        "2": {
            "terms": {
                "field": "tag.country.keyword",
                "size": 20,
                "min_doc_count": 1,
                "shard_min_doc_count": 0,
                "show_term_doc_count_error": false,
                "order": [
                    {
                        "1": "desc"
                    },
                    {
                        "_key": "asc"
                    }
                ]
            },
            "aggregations": {
                "1": {
                    "avg": {
                        "field": "my_field"
                    }
                }
            }
        }
    }
}

Here, I'm talking about the "avg" aggregation at the very bottom. As I understand, right below the "field" key, I should specify a "script" key, defining the rounding function that I want to use. Can anybody help me come up with the correct function?

I'm not sure what to specify in the "script" key to make the rounding function work.