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	$196.69	6.731%	$209.9292	$209.93	$209.95	$209.90
Purchase #2	$54.67	11.776%	$61.1079	$61.11	$61.10	$61.10
Purchase #3	$246.47	11.617%	$275.1024	$275.10	$275.10	$275.10
Purchase #4	$151.99	3.167%	$156.8035	$156.80	$156.80	$156.80
Purchase #5	$121.42	5.120%	$127.6367	$127.64	$127.65	$127.60
Purchase #6	$194.56	11.261%	$216.4694	$216.47	$216.45	$216.50
Purchase #7	$78.49	9.210%	$85.7189	$85.72	$85.70	$85.70
7 purchase totals =	$1,044.29		$1,132.7680	$1,132.77	$1,132.75	$1,132.70