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	$101.52	10.178%	$111.8527	$111.85	$111.85	$111.90
Purchase #2	$115.48	6.799%	$123.3315	$123.33	$123.35	$123.30
Purchase #3	$49.71	7.578%	$53.477	$53.48	$53.50	$53.50
Purchase #4	$185.73	3.235%	$191.7384	$191.74	$191.75	$191.70
Purchase #5	$175.57	13.814%	$199.8232	$199.82	$199.80	$199.80
Purchase #6	$108.92	10.271%	$120.1072	$120.11	$120.10	$120.10
Purchase #7	$149.49	3.214%	$154.2946	$154.29	$154.30	$154.30
7 purchase totals =	$886.42		$954.6246	$954.62	$954.65	$954.60