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	$172.31	13.289%	$195.2083	$195.21	$195.20	$195.20
Purchase #2	$75.43	4.391%	$78.7421	$78.74	$78.75	$78.70
Purchase #3	$67.49	7.103%	$72.2838	$72.28	$72.30	$72.30
Purchase #4	$67.96	13.753%	$77.3065	$77.31	$77.30	$77.30
Purchase #5	$163.65	3.414%	$169.237	$169.24	$169.25	$169.20
Purchase #6	$210.33	5.197%	$221.2609	$221.26	$221.25	$221.30
Purchase #7	$193.37	3.180%	$199.5192	$199.52	$199.50	$199.50
7 purchase totals =	$950.54		$1,013.5578	$1,013.56	$1,013.55	$1,013.50