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	$111.63	7.121%	$119.5792	$119.58	$119.60	$119.60
Purchase #2	$106.28	9.708%	$116.5977	$116.60	$116.60	$116.60
Purchase #3	$99.43	12.541%	$111.8995	$111.90	$111.90	$111.90
Purchase #4	$68.40	12.281%	$76.8002	$76.80	$76.80	$76.80
Purchase #5	$190.25	4.394%	$198.6096	$198.61	$198.60	$198.60
Purchase #6	$161.63	5.654%	$170.7686	$170.77	$170.75	$170.80
Purchase #7	$88.26	13.842%	$100.4769	$100.48	$100.50	$100.50
7 purchase totals =	$825.88		$894.7317	$894.74	$894.75	$894.80