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	$91.57	4.482%	$95.6742	$95.67	$95.65	$95.70
Purchase #2	$49.45	7.203%	$53.0119	$53.01	$53.00	$53.00
Purchase #3	$196.74	11.118%	$218.6136	$218.61	$218.60	$218.60
Purchase #4	$80.64	5.606%	$85.1607	$85.16	$85.15	$85.20
Purchase #5	$88.42	4.369%	$92.2831	$92.28	$92.30	$92.30
Purchase #6	$183.74	4.337%	$191.7088	$191.71	$191.70	$191.70
Purchase #7	$242.60	11.475%	$270.4384	$270.44	$270.45	$270.40
7 purchase totals =	$933.16		$1,006.8907	$1,006.88	$1,006.85	$1,006.90