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	$209.33	4.168%	$218.0549	$218.05	$218.05	$218.10
Purchase #2	$6.90	11.113%	$7.6668	$7.67	$7.65	$7.70
Purchase #3	$193.52	3.839%	$200.9492	$200.95	$200.95	$200.90
Purchase #4	$163.29	5.621%	$172.4685	$172.47	$172.45	$172.50
Purchase #5	$69.34	7.606%	$74.614	$74.61	$74.60	$74.60
Purchase #6	$85.32	6.205%	$90.6141	$90.61	$90.60	$90.60
Purchase #7	$205.25	13.597%	$233.1578	$233.16	$233.15	$233.20
7 purchase totals =	$932.95		$997.5253	$997.52	$997.45	$997.60