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	$171.25	9.585%	$187.6643	$187.66	$187.65	$187.70
Purchase #2	$204.83	9.324%	$223.9283	$223.93	$223.95	$223.90
Purchase #3	$235.81	5.341%	$248.4046	$248.40	$248.40	$248.40
Purchase #4	$58.68	6.410%	$62.4414	$62.44	$62.45	$62.40
Purchase #5	$86.54	5.765%	$91.529	$91.53	$91.55	$91.50
Purchase #6	$71.55	10.208%	$78.8538	$78.85	$78.85	$78.90
Purchase #7	$150.56	10.461%	$166.3101	$166.31	$166.30	$166.30
7 purchase totals =	$979.22		$1,059.1315	$1,059.12	$1,059.15	$1,059.10