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	$198.25	8.343%	$214.79	$214.79	$214.80	$214.80
Purchase #2	$88.69	8.123%	$95.8943	$95.89	$95.90	$95.90
Purchase #3	$178.31	3.453%	$184.467	$184.47	$184.45	$184.50
Purchase #4	$65.65	8.847%	$71.4581	$71.46	$71.45	$71.50
Purchase #5	$233.25	4.148%	$242.9252	$242.93	$242.95	$242.90
Purchase #6	$13.27	6.815%	$14.1744	$14.17	$14.15	$14.20
Purchase #7	$50.40	10.552%	$55.7182	$55.72	$55.70	$55.70
7 purchase totals =	$827.82		$879.4272	$879.43	$879.40	$879.50