What pricing trick involves setting a price just below a round number, like $9.99 instead of $10.00?

The pricing trick involving setting a price just below a round number, like $9.99 instead of $10.00, is known as charm pricing or psychological pricing. This strategy leverages the left-digit effect, a cognitive bias where consumers primarily focus on the leftmost digit of a price, perceiving a price ending in .99 as belonging to the lower preceding dollar amount rather than the next higher one. For instance, $9.99 is psychologically processed more as 'nine dollars and something' than 'almost ten dollars,' creating a mental anchor at the lower value. This effect occurs because people read numbers from left to right, and the initial digits are encoded more strongly, often leading to a subconscious truncation or rounding down of the price. Prices ending in .99 are also historically associated with sales, promotions, or a 'good deal,' further enhancing the perception of value and affordability. This technique subtly influences consumer perception, making products appear more attractive and increasing the likelihood of purchase without a significant actual price reduction.