Amazon has Sensodyne Toothpaste (various) on sale as listed below when you change the quantity to 3 and checkout via Subscribe & Save. Shipping is free w/ Prime or on $25+ orders.
Available Options
2-Count 4oz Sensodyne Pronamel Toothpaste (Fresh Wave) 3 for $18.94
4oz Sensodyne Pronamel Multi-Action Enamel Toothpaste (Cleansing Mint) 3 for $10.58
3.4oz Sensodyne Complete Protection Toothpaste (Extra Fresh) 3 for $10.58
3.4oz Sensodyne Repair & Protect Sensitive Toothpaste 3 for $11.58