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	$235.70	11.341%	$262.4307	$262.43	$262.45	$262.40
Purchase #2	$134.55	3.665%	$139.4813	$139.48	$139.50	$139.50
Purchase #3	$214.58	10.802%	$237.7589	$237.76	$237.75	$237.80
Purchase #4	$42.45	12.383%	$47.7066	$47.71	$47.70	$47.70
Purchase #5	$159.46	5.740%	$168.613	$168.61	$168.60	$168.60
Purchase #6	$94.89	6.354%	$100.9193	$100.92	$100.90	$100.90
Purchase #7	$211.56	3.623%	$219.2248	$219.22	$219.20	$219.20
7 purchase totals =	$1,093.19		$1,176.1346	$1,176.13	$1,176.10	$1,176.10