Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$83.50	4.659%	$87.3903	$87.39	$87.40	$87.40
Purchase #2	$113.40	4.586%	$118.6005	$118.60	$118.60	$118.60
Purchase #3	$235.65	13.644%	$267.8021	$267.80	$267.80	$267.80
Purchase #4	$17.29	12.300%	$19.4167	$19.42	$19.40	$19.40
Purchase #5	$212.32	4.677%	$222.2502	$222.25	$222.25	$222.30
Purchase #6	$127.30	3.393%	$131.6193	$131.62	$131.60	$131.60
Purchase #7	$158.61	8.362%	$171.873	$171.87	$171.85	$171.90
7 purchase totals =	$948.07		$1,018.9521	$1,018.95	$1,018.90	$1,019.00