Kautilya's Arthashastra 2.21.13

2.21.13

pratikretṛbhayād vā paṇyamūlyād upari mūlyaṃ vardhayato mūlyavṛddhiṃ rājā haret, dviguṇaṃ vā śulkaṃ kuryāt //

When under the fear of bidders (enhancing the price), the price of any merchandise is increased beyond its proper value, the king shall receive the enhanced amount or twice the amount of toll on it. The same punishment or eight times the amount of toll shall be imposed on the Superintendent of tolls if he conceals (merchandise).