Selling

Selling is a game mechanic first introduced in the original Bloons TD. It involves the removal of towers while returning back a percentage of the money spent on placement and upgrades. In Bloons Monkey City and Bloons Adventure Time TD (also BTD6 with Max towers (types of towers) or Odyssey Mode?), selling also returns the sold tower back to the towers menu for use again. (Special Agents and powers selling in game?)

Sellback is the amount of cash earned from selling. In games before Bloons TD 6, this sellback percentage is 75%, except in Bloons TD Battles Flash where it is 70%. In Bloons TD 6, default sellback is 70%, but caps at 95% sellback, and similarly applies for Bloons TD Battles 2. In Bloons Adventure Time TD, the default sellback is 70%. In Bloons Monkey City and Bloons Monkey City Mobile, the default sellback is 75% but can be increased with achieving higher-ranked Monkey Tycoon Monkey Knowledge.

In Bloons TD 6, attempting to sell towers in a game where selling is disabled (e.g. Daily Challenges/Custom Challenges with No Selling enabled or CHIMPS mode) via the secret in Flooded Valley or moving an Arctic Wind using a Support Chinook to cause non-water towers to "fall" into water will return $0 per sold tower. CHIMPS will also return $0 for any sold towers even if selling is forcibly enabled in the Challenge Editor. However, Sentry Champion's Champion Sentries can still be sold in CHIMPS. Selling towers while Lych is active will heal it by a certain percentage.

Sellback sources
In BTD4, the only method of increasing sellback is via the Monkey Tycoon premium item.

In BTD5, Monkey Tycoon is the only method in BTD5 Flash and Deluxe, though in BTD5 Mobile and Steam there are Monkey Lab perks that increase sellback.

In BTD6, there are multiple methods of adding extra sellback:


 * +5% with "Better Sell Deals" MK
 * +10% with Favored Trades
 * +10% with Banana Salvage (but limited to the BTD6 Banana Farm)
 * +2% with "Flat Pack Buildings" MK, exclusive to BTD6 Monkey Village BTD6 Banana Farm

Sounds
There are no selling sounds for pre-BTD4 games.

When the player sells in BTD4 Generation games:


 * [coin dollop]

When the player sells in BTD5 Generation games:


 * [coin clinking]

When the player sells a powerup in BSM2 Mobile:


 * [TBA]

When the player sells in BTD6 Generation games:


 * [cash shake]

Trivia

 * In all game generations, at least from Bloons TD 4 Generation onwards, the selling sound is always the same for games sharing the same generation, but is different in each distinct game generation.