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	$211.46	10.395%	$233.4413	$233.44	$233.45	$233.40
Purchase #2	$53.28	13.707%	$60.5831	$60.58	$60.60	$60.60
Purchase #3	$136.81	10.298%	$150.8987	$150.90	$150.90	$150.90
Purchase #4	$224.75	13.300%	$254.6418	$254.64	$254.65	$254.60
Purchase #5	$65.72	3.178%	$67.8086	$67.81	$67.80	$67.80
Purchase #6	$188.43	9.186%	$205.7392	$205.74	$205.75	$205.70
Purchase #7	$44.27	4.743%	$46.3697	$46.37	$46.35	$46.40
7 purchase totals =	$924.72		$1,019.4824	$1,019.48	$1,019.50	$1,019.40