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	$88.52	7.868%	$95.4848	$95.48	$95.50	$95.50
Purchase #2	$9.47	9.326%	$10.3532	$10.35	$10.35	$10.40
Purchase #3	$99.29	13.257%	$112.4529	$112.45	$112.45	$112.50
Purchase #4	$59.34	8.844%	$64.588	$64.59	$64.60	$64.60
Purchase #5	$107.77	7.293%	$115.6297	$115.63	$115.65	$115.60
Purchase #6	$12.77	5.532%	$13.4764	$13.48	$13.50	$13.50
Purchase #7	$136.66	4.873%	$143.3194	$143.32	$143.30	$143.30
7 purchase totals =	$513.82		$555.3044	$555.30	$555.35	$555.40