Event Confirmation and ThankYou forms show tax rate with ALL the decimal places.
These pages are not yet using the new
CRM_Financial_Form_FrontEndPaymentFormTrait to assign line items to their template, but they should.
From a mis-comment or two in #1043; this is not the same as the decimal places in the prices, but it is the same issue as what's addressed in @mattwire's additional PR on #1043 (comment 19038) and is related to the work @eileen has done in PR 13889
Agileware ref. CIVICRM-1244
Will request pulls shortly.