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	$59.43	3.784%	$61.6788	$61.68	$61.70	$61.70
Purchase #2	$97.56	10.840%	$108.1355	$108.14	$108.15	$108.10
Purchase #3	$179.43	9.244%	$196.0165	$196.02	$196.00	$196.00
Purchase #4	$195.74	5.587%	$206.676	$206.68	$206.70	$206.70
Purchase #5	$139.57	13.608%	$158.5627	$158.56	$158.55	$158.60
Purchase #6	$85.51	4.849%	$89.6564	$89.66	$89.65	$89.70
Purchase #7	$199.89	5.642%	$211.1678	$211.17	$211.15	$211.20
7 purchase totals =	$957.13		$1,031.8937	$1,031.91	$1,031.90	$1,032.00