MCP server

Penny Rounding

com.gumballtools/penny-rounding

Checked 26 Oct 2026, 08:29 UTC · Connected to it and listed its tools

Round cash totals to the nearest nickel correctly — after tax, on the total, cash only.

Working at last checkVerified publisher: gumballtools.comAbout 2,188 tokens per request once connected3 tools

https://penny-rounding.gumballtools.com/api/mcp

At a glance

Type: MCP server
Publisher: gumballtools.com (verified by the MCP Registry)
Status: Working at last check
Tools: 3
Token cost: About 2,188 tokens per request
Sets up in: Claude Code, Claude Desktop, Codex, Gemini CLI, Cursor, VS Code, Antigravity, ChatGPT, OpenAI API, Grok
Last checked: 26 Oct 2026, 08:29 UTC

Opens the app, which shows the server and asks you to confirm. For other apps, copy the setup below.

Claude Code

claude mcp add --transport http penny-rounding https://penny-rounding.gumballtools.com/api/mcp

Claude Desktop

Settings → Connectors → Add custom connector, and paste the URL.

Codex (config.toml)

[mcp_servers.penny-rounding]
url = "https://penny-rounding.gumballtools.com/api/mcp"

Gemini CLI

{"mcpServers":{"penny-rounding":{"httpUrl":"https://penny-rounding.gumballtools.com/api/mcp"}}}

Cursor

{"mcpServers":{"penny-rounding":{"url":"https://penny-rounding.gumballtools.com/api/mcp"}}}

VS Code

{"servers":{"penny-rounding":{"type":"http","url":"https://penny-rounding.gumballtools.com/api/mcp"}}}

Antigravity

agy mcp add penny-rounding https://penny-rounding.gumballtools.com/api/mcp

ChatGPT

Settings → Apps & Connectors → Advanced settings: turn on Developer mode, then Create a connector and paste the URL. Which plans can do this varies.

OpenAI API (Responses tools)

{"type":"mcp","server_label":"penny-rounding","server_url":"https://penny-rounding.gumballtools.com/api/mcp","require_approval":"always"}

Grok (xAI API tools)

{"type":"mcp","server_label":"penny-rounding","server_url":"https://penny-rounding.gumballtools.com/api/mcp"}

price_band ~647 tokens
For a list price and a tax rate, find every nearby list price that settles to the SAME cash total, and the highest one. Use this for "what price should I charge" and "can I price to gain from rounding" questions. There is exactly one free move here and it is easy to get backwards, so do not reason
round_cash_total ~937 tokens
Settle a transaction under post-penny cash rounding: exact subtotal, tax on the exact subtotal, then round the final total to the nearest nickel — and only for cash. Use this for any "what does X round to" or "what do I owe in cash" question. Four things are wrong in most explanations of this, and
rounding_impact ~604 tokens
Compute what cash rounding is actually worth across a list of prices: mean delta per transaction, the up/down/unchanged split, and a per-thousand figure. Use this whenever someone asks whether rounding costs or earns money — a very common question and one usually answered with a guess. Do not guess

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