Lightspeed Retail does not support fractional quantities. This cannot be modified or changed. This article explains how the Hyperspace Weight Scale Application works in order to enable fractional quantities to function.
Cashiers can weigh different items on one sale or return to the sale in Lightspeed Retail at anytime. Once the cashier returns to the sale in Lightspeed Retail, all products and prices will be pre-populated into the sale.
The Cashier clicks the Weight button in Lightspeed Retail and a new tab appears that enables the Cashier to weigh the items. The price per increment is auto-calculated for the Cashier. See below.
The Weight Application does not manage inventory. The fractional amount that is weighed appears on the line item on the sale. The fractional amount that is weighed also appears on the receipt in Lightspeed Retail that is given to the customer.
The actual stock that is reduced in Lightspeed Retail is always 1 unit per line item. It is designed for retailers that sell items in bins or bulk.
There is no option to sell or adjust stock in increments using Lightspeed Retail. The only add-on to this solution that could help would be an end of day incremental stock report that would notify you about stock that was sold through the Application.