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	$167.68	9.761%	$184.0472	$184.05	$184.05	$184.00
Purchase #2	$189.35	4.638%	$198.1321	$198.13	$198.15	$198.10
Purchase #3	$158.35	9.488%	$173.3742	$173.37	$173.35	$173.40
Purchase #4	$80.41	10.868%	$89.149	$89.15	$89.15	$89.10
Purchase #5	$110.76	11.591%	$123.5982	$123.60	$123.60	$123.60
Purchase #6	$60.72	7.814%	$65.4647	$65.46	$65.45	$65.50
Purchase #7	$195.78	9.162%	$213.7174	$213.72	$213.70	$213.70
7 purchase totals =	$963.05		$1,047.4828	$1,047.48	$1,047.45	$1,047.40