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	$98.61	8.670%	$107.1595	$107.16	$107.15	$107.20
Purchase #2	$231.82	11.566%	$258.6323	$258.63	$258.65	$258.60
Purchase #3	$203.83	8.862%	$221.8934	$221.89	$221.90	$221.90
Purchase #4	$18.61	12.164%	$20.8737	$20.87	$20.85	$20.90
Purchase #5	$54.46	12.796%	$61.4287	$61.43	$61.45	$61.40
Purchase #6	$238.31	3.325%	$246.2338	$246.23	$246.25	$246.20
Purchase #7	$105.87	12.163%	$118.747	$118.75	$118.75	$118.70
7 purchase totals =	$951.51		$1,034.9684	$1,034.96	$1,035.00	$1,034.90