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	$191.42	4.694%	$200.4053	$200.41	$200.40	$200.40
Purchase #2	$211.26	3.581%	$218.8252	$218.83	$218.85	$218.80
Purchase #3	$92.45	13.416%	$104.8531	$104.85	$104.85	$104.90
Purchase #4	$242.27	4.284%	$252.6488	$252.65	$252.65	$252.60
Purchase #5	$40.80	9.333%	$44.6079	$44.61	$44.60	$44.60
Purchase #6	$67.37	13.285%	$76.3201	$76.32	$76.30	$76.30
Purchase #7	$237.32	4.418%	$247.8048	$247.80	$247.80	$247.80
7 purchase totals =	$1,082.89		$1,145.4652	$1,145.47	$1,145.45	$1,145.40