Entity card showing monthly electricity cost of 2 plugs

Configuration
1

I use this code to track the combined kWh energy usage of 2 sonoff s31 plugs, then I calculate the electricity cost. But I can’t figure out how to display the sum of the last 30 days electricity cost in an entity card

sensor:
  - platform: integration
    source: sensor.sonoff_10014f7842_power
    name: grow_tent1_kWh
    unit_prefix: k
    unit: kWh
    round: 2


      all_grow_tent_kwh_cost:
        friendly_name: "Total electricity cost (Grow tents)"
        unit_of_measurement: '$'
        value_template: "
        {{ 
            ( float(states('sensor.grow_tent1_kwh')) + float(states('sensor.grow_tent2_kwh')) ) * 0.09502
        }}
        "