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	$190.41	3.179%	$196.4631	$196.46	$196.45	$196.50
Purchase #2	$181.30	12.803%	$204.5118	$204.51	$204.50	$204.50
Purchase #3	$32.52	4.774%	$34.0725	$34.07	$34.05	$34.10
Purchase #4	$178.91	11.574%	$199.617	$199.62	$199.60	$199.60
Purchase #5	$160.47	6.143%	$170.3277	$170.33	$170.35	$170.30
Purchase #6	$248.42	11.281%	$276.4443	$276.44	$276.45	$276.40
Purchase #7	$12.54	9.667%	$13.7522	$13.75	$13.75	$13.80
7 purchase totals =	$1,004.57		$1,095.1886	$1,095.18	$1,095.15	$1,095.20