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	$196.46	7.291%	$210.7839	$210.78	$210.80	$210.80
Purchase #2	$76.80	7.689%	$82.7052	$82.71	$82.70	$82.70
Purchase #3	$148.66	6.376%	$158.1386	$158.14	$158.15	$158.10
Purchase #4	$224.72	5.181%	$236.3627	$236.36	$236.35	$236.40
Purchase #5	$194.57	8.507%	$211.1221	$211.12	$211.10	$211.10
Purchase #6	$54.66	12.494%	$61.4892	$61.49	$61.50	$61.50
Purchase #7	$99.30	13.128%	$112.3361	$112.34	$112.35	$112.30
7 purchase totals =	$995.17		$1,072.9378	$1,072.94	$1,072.95	$1,072.90