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	$176.54	13.235%	$199.9051	$199.91	$199.90	$199.90
Purchase #2	$99.99	11.136%	$111.1249	$111.12	$111.10	$111.10
Purchase #3	$77.53	11.164%	$86.1854	$86.19	$86.20	$86.20
Purchase #4	$229.59	8.496%	$249.096	$249.10	$249.10	$249.10
Purchase #5	$29.39	11.243%	$32.6943	$32.69	$32.70	$32.70
Purchase #6	$209.45	6.194%	$222.4233	$222.42	$222.40	$222.40
Purchase #7	$106.36	6.404%	$113.1713	$113.17	$113.15	$113.20
7 purchase totals =	$928.85		$1,014.6003	$1,014.60	$1,014.55	$1,014.60