Decimals
Watch the explanation for this recipe in the video Check The Element Contains A Number That Ends With Two Decimals.
Two decimals
Let's confirm the element has text that ends with two decimal numbers.
<div id="amount">1,465.30</div>
cy.contains('#amount', /\.\d\d$/)
Optional zero last decimal
Sometimes the last digit is optional, if it is zero.
<div id="amount">1,465.3</div>
cy.contains('#amount', /\.\d\d?$/)
Tip: In Cypress v12 you can get the text of the element and invoke the regular expression match method, see cypress-map