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	$229.31	6.794%	$244.8893	$244.89	$244.90	$244.90
Purchase #2	$221.55	9.718%	$243.0802	$243.08	$243.10	$243.10
Purchase #3	$192.39	4.385%	$200.8263	$200.83	$200.85	$200.80
Purchase #4	$204.51	3.704%	$212.0851	$212.09	$212.10	$212.10
Purchase #5	$90.25	13.116%	$102.0872	$102.09	$102.10	$102.10
Purchase #6	$233.91	5.335%	$246.3891	$246.39	$246.40	$246.40
Purchase #7	$174.27	12.472%	$196.005	$196.01	$196.00	$196.00
7 purchase totals =	$1,346.19		$1,445.3622	$1,445.38	$1,445.45	$1,445.40