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	$98.44	4.477%	$102.8472	$102.85	$102.85	$102.80
Purchase #2	$149.83	8.147%	$162.0367	$162.04	$162.05	$162.00
Purchase #3	$58.58	6.401%	$62.3297	$62.33	$62.35	$62.30
Purchase #4	$124.38	3.387%	$128.5928	$128.59	$128.60	$128.60
Purchase #5	$59.47	13.111%	$67.2671	$67.27	$67.25	$67.30
Purchase #6	$53.90	11.534%	$60.1168	$60.12	$60.10	$60.10
Purchase #7	$104.83	11.563%	$116.9515	$116.95	$116.95	$117.00
7 purchase totals =	$649.43		$700.1418	$700.15	$700.15	$700.10