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	$43.51	8.169%	$47.0643	$47.06	$47.05	$47.10
Purchase #2	$155.38	10.139%	$171.134	$171.13	$171.15	$171.10
Purchase #3	$190.51	13.619%	$216.4556	$216.46	$216.45	$216.50
Purchase #4	$247.67	3.413%	$256.123	$256.12	$256.10	$256.10
Purchase #5	$47.74	5.548%	$50.3886	$50.39	$50.40	$50.40
Purchase #6	$185.80	5.803%	$196.582	$196.58	$196.60	$196.60
Purchase #7	$173.47	12.517%	$195.1832	$195.18	$195.20	$195.20
7 purchase totals =	$1,044.08		$1,132.9307	$1,132.92	$1,132.95	$1,133.00