Not getting specific costs associated with allocation tags

Question

I am building a python dashboard so that my clients who I have applications hosted on AWS can pay the exact amount there project costs me. I am using the python sdk but I only get my accounts overall amounts from my queries.

I have been sure to add the tags to the projects (ex: elastic beanstalk) and activated the cost allocation tags but it has been to no avail.

cost_allocation_tag = 'Company'

client = boto3.client(
    'ce',
    aws_access_key_id=aws_access_key_id,
    aws_secret_access_key=aws_secret_access_key,
)

try:
    monthly = client.get_cost_and_usage(
            TimePeriod={
                'Start':end,
                'End':now.strftime('%Y-%m-%d')
            },
            Granularity='MONTHLY',
            Metrics=[
            'BlendedCost',
            ],
            GroupBy=[
            {
                'Type': 'TAG',
                'Key': cost_allocation_tag
            },
            ]
        )
    monthly_cost = monthly['ResultsByTime'][0]['Groups'][0]['Metrics']['BlendedCost']['Amount']
except:
    pass

I should get costs only associated with the tags not the overall. I have read the documentation but I am not 100% on if I followed it correctly. Here is the link to the docs

https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/ce.html#CostExplorer.Client.get_cost_and_usage