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	$196.85	13.144%	$222.724	$222.72	$222.70	$222.70
Purchase #2	$202.63	3.136%	$208.9845	$208.98	$209.00	$209.00
Purchase #3	$40.74	8.752%	$44.3056	$44.31	$44.30	$44.30
Purchase #4	$155.83	12.363%	$175.0953	$175.10	$175.10	$175.10
Purchase #5	$220.35	12.398%	$247.669	$247.67	$247.65	$247.70
Purchase #6	$86.74	11.321%	$96.5598	$96.56	$96.55	$96.60
Purchase #7	$71.89	9.282%	$78.5628	$78.56	$78.55	$78.60
7 purchase totals =	$975.03		$1,073.9010	$1,073.90	$1,073.85	$1,074.00