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	$40.36	10.276%	$44.5074	$44.51	$44.50	$44.50
Purchase #2	$220.51	6.791%	$235.4848	$235.48	$235.50	$235.50
Purchase #3	$50.55	4.604%	$52.8773	$52.88	$52.90	$52.90
Purchase #4	$185.69	12.302%	$208.5336	$208.53	$208.55	$208.50
Purchase #5	$204.90	11.321%	$228.0967	$228.10	$228.10	$228.10
Purchase #6	$230.77	4.257%	$240.5939	$240.59	$240.60	$240.60
Purchase #7	$112.69	9.399%	$123.2817	$123.28	$123.30	$123.30
7 purchase totals =	$1,045.47		$1,133.3754	$1,133.37	$1,133.45	$1,133.40