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	$85.85	4.538%	$89.7459	$89.75	$89.75	$89.70
Purchase #2	$70.70	5.295%	$74.4436	$74.44	$74.45	$74.40
Purchase #3	$42.84	11.793%	$47.8921	$47.89	$47.90	$47.90
Purchase #4	$189.51	10.538%	$209.4806	$209.48	$209.50	$209.50
Purchase #5	$235.67	7.409%	$253.1308	$253.13	$253.15	$253.10
Purchase #6	$198.68	13.639%	$225.778	$225.78	$225.80	$225.80
Purchase #7	$113.83	8.550%	$123.5625	$123.56	$123.55	$123.60
7 purchase totals =	$937.08		$1,024.0335	$1,024.03	$1,024.10	$1,024.00