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	$197.56	11.166%	$219.6195	$219.62	$219.60	$219.60
Purchase #2	$87.88	8.433%	$95.2909	$95.29	$95.30	$95.30
Purchase #3	$96.38	13.825%	$109.7045	$109.70	$109.70	$109.70
Purchase #4	$76.46	6.816%	$81.6715	$81.67	$81.65	$81.70
Purchase #5	$75.54	9.205%	$82.4935	$82.49	$82.50	$82.50
Purchase #6	$235.87	8.362%	$255.5934	$255.59	$255.60	$255.60
Purchase #7	$165.45	3.131%	$170.6302	$170.63	$170.65	$170.60
7 purchase totals =	$935.14		$1,015.0035	$1,014.99	$1,015.00	$1,015.00