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	$162.56	11.162%	$180.7049	$180.70	$180.70	$180.70
Purchase #2	$204.97	4.205%	$213.589	$213.59	$213.60	$213.60
Purchase #3	$192.63	11.161%	$214.1294	$214.13	$214.15	$214.10
Purchase #4	$146.36	6.295%	$155.5734	$155.57	$155.55	$155.60
Purchase #5	$95.95	10.363%	$105.8933	$105.89	$105.90	$105.90
Purchase #6	$110.48	11.576%	$123.2692	$123.27	$123.25	$123.30
Purchase #7	$203.88	7.833%	$219.8499	$219.85	$219.85	$219.80
7 purchase totals =	$1,116.83		$1,213.0091	$1,213.00	$1,213.00	$1,213.00