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	$148.25	10.543%	$163.88	$163.88	$163.90	$163.90
Purchase #2	$93.86	7.323%	$100.7334	$100.73	$100.75	$100.70
Purchase #3	$235.46	5.169%	$247.6309	$247.63	$247.65	$247.60
Purchase #4	$47.33	3.312%	$48.8976	$48.90	$48.90	$48.90
Purchase #5	$95.90	8.594%	$104.1416	$104.14	$104.15	$104.10
Purchase #6	$51.54	7.690%	$55.5034	$55.50	$55.50	$55.50
Purchase #7	$54.85	12.682%	$61.8061	$61.81	$61.80	$61.80
7 purchase totals =	$727.19		$782.5930	$782.59	$782.65	$782.50