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	$104.47	5.784%	$110.5125	$110.51	$110.50	$110.50
Purchase #2	$32.90	5.328%	$34.6529	$34.65	$34.65	$34.70
Purchase #3	$115.84	7.280%	$124.2732	$124.27	$124.25	$124.30
Purchase #4	$119.86	9.253%	$130.9506	$130.95	$130.95	$131.00
Purchase #5	$233.83	9.643%	$256.3782	$256.38	$256.40	$256.40
Purchase #6	$234.26	8.321%	$253.7528	$253.75	$253.75	$253.80
Purchase #7	$100.99	5.333%	$106.3758	$106.38	$106.40	$106.40
7 purchase totals =	$942.15		$1,016.8960	$1,016.89	$1,016.90	$1,017.10