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	$43.88	3.843%	$45.5663	$45.57	$45.55	$45.60
Purchase #2	$94.78	5.772%	$100.2507	$100.25	$100.25	$100.30
Purchase #3	$166.52	3.145%	$171.7571	$171.76	$171.75	$171.80
Purchase #4	$174.53	12.710%	$196.7128	$196.71	$196.70	$196.70
Purchase #5	$111.47	8.813%	$121.2939	$121.29	$121.30	$121.30
Purchase #6	$250.59	8.325%	$271.4516	$271.45	$271.45	$271.50
Purchase #7	$234.48	4.823%	$245.789	$245.79	$245.80	$245.80
7 purchase totals =	$1,076.25		$1,152.8214	$1,152.82	$1,152.80	$1,153.00