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	$193.76	8.481%	$210.1928	$210.19	$210.20	$210.20
Purchase #2	$12.52	7.261%	$13.4291	$13.43	$13.45	$13.40
Purchase #3	$51.72	11.346%	$57.5882	$57.59	$57.60	$57.60
Purchase #4	$249.31	5.316%	$262.5633	$262.56	$262.55	$262.60
Purchase #5	$117.65	6.634%	$125.4549	$125.45	$125.45	$125.50
Purchase #6	$123.37	3.376%	$127.535	$127.54	$127.55	$127.50
Purchase #7	$203.53	12.403%	$228.7738	$228.77	$228.75	$228.80
7 purchase totals =	$951.86		$1,025.5371	$1,025.53	$1,025.55	$1,025.60