SuitePOS considers this depending on how the pricing calculation is defined on the item record (by line quantity or overall line quantity).
Navigation : Setup > Company > Enable Features > Transactions Tab > ‘Sales’ Field Group > Check ‘Quantity Pricing’ checkbox.

Quantity Pricing Explained :
If this feature is enabled, the pricing of the item now considers all the price breaks available for that particular item. From the example below, if one bottle of wine is purchased, the price is 10.00. If 6 are purchased, all 6 are now priced at 9.00.
In addition, there may be various price levels available. For example, if an Employee (named customer) purchases 24 bottles of wine, the price is 6.666.
For POS Purposes: “Use Marginal Rates” should always be unchecked otherwise the Quantity Pricing is ignored.

Tip
Serialized items or items where merge is “Off”, it is suggested you set “Calculate Quantity Discount” on the line item to ‘Overall Line” item. Otherwise Quantity pricing will not be considered (by default).
LIMITATIONS :
Item Size Issues
When Quantity Pricing is enabled, you can end up with the “effective” item count growing exponentially. This will increase sync times, perhaps even to the point of timing out and/or causing CONCURRENT REQUESTS issues which will make most of your terminals fail the item sync.
Note:
SuitePOS always rounds currency amounts to the nearest 2 decimal places. This may affect the calculation of total cost for a line item on a POS transaction when the unit price of an item is specified with more then 2 decimal places (in NetSuite). This can affect a single quantity, calculated UOM price or Quantity Pricing calculation in SuitePOS.
Example:
Item A Quantity Pricing for a Quantity of “2” = $1.125 (as set in NetSuite)
In NetSuite, quantity 2 of Item A would result in a total item price of $2.25 on a transaction.
In SuitePOS, quantity 2 of item A would result in a total item price of $2.26.
Note
If “Enable Quantity Pricing” is changed on POS Settings a FULL SYNC is required on ALL terminals.
Note:
It is possible for a given price-level for the price of the item to be blank. If thats the case, the base price (with respect to the quantity pricing) will be used as the default. This is useful when you do not want to set pricing for all items at every level and quantity break.