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	$221.83	10.394%	$244.887	$244.89	$244.90	$244.90
Purchase #2	$89.88	7.413%	$96.5428	$96.54	$96.55	$96.50
Purchase #3	$233.91	12.253%	$262.571	$262.57	$262.55	$262.60
Purchase #4	$230.66	12.445%	$259.3656	$259.37	$259.35	$259.40
Purchase #5	$54.31	13.143%	$61.448	$61.45	$61.45	$61.40
Purchase #6	$23.70	7.419%	$25.4583	$25.46	$25.45	$25.50
Purchase #7	$104.82	7.845%	$113.0431	$113.04	$113.05	$113.00
7 purchase totals =	$959.11		$1,063.3158	$1,063.32	$1,063.30	$1,063.30