Originally with reference to the fact that if one owed a penny, one might as well owe a pound (pound sterling, UK currency) as the penalties for non-payment were virtually identical in severity.
in-for-a-penny-in-for-a-pound

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"in-for-a-penny-in-for-a-pound." YourDictionary, n.d. Web. 19 January 2019. <https://www.yourdictionary.com/in-for-a-penny-in-for-a-pound>.
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in-for-a-penny-in-for-a-pound. (n.d.). Retrieved January 19th, 2019, from https://www.yourdictionary.com/in-for-a-penny-in-for-a-pound