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	$55.54	3.714%	$57.6028	$57.60	$57.60	$57.60
Purchase #2	$97.55	9.790%	$107.1001	$107.10	$107.10	$107.10
Purchase #3	$151.30	10.618%	$167.365	$167.37	$167.35	$167.40
Purchase #4	$67.36	6.229%	$71.5559	$71.56	$71.55	$71.60
Purchase #5	$64.89	3.760%	$67.3299	$67.33	$67.35	$67.30
Purchase #6	$12.54	8.605%	$13.6191	$13.62	$13.60	$13.60
Purchase #7	$230.59	7.747%	$248.4538	$248.45	$248.45	$248.50
7 purchase totals =	$679.77		$733.0266	$733.03	$733.00	$733.10