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	$77.32	11.521%	$86.228	$86.23	$86.25	$86.20
Purchase #2	$57.38	3.422%	$59.3435	$59.34	$59.35	$59.30
Purchase #3	$122.81	13.253%	$139.086	$139.09	$139.10	$139.10
Purchase #4	$200.84	6.283%	$213.4588	$213.46	$213.45	$213.50
Purchase #5	$54.33	12.544%	$61.1452	$61.15	$61.15	$61.10
Purchase #6	$54.96	12.158%	$61.642	$61.64	$61.65	$61.60
Purchase #7	$40.38	3.311%	$41.717	$41.72	$41.70	$41.70
7 purchase totals =	$608.02		$662.6205	$662.63	$662.65	$662.50