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	$182.25	7.840%	$196.5384	$196.54	$196.55	$196.50
Purchase #2	$99.45	13.616%	$112.9911	$112.99	$113.00	$113.00
Purchase #3	$56.28	5.312%	$59.2696	$59.27	$59.25	$59.30
Purchase #4	$169.74	3.625%	$175.8931	$175.89	$175.90	$175.90
Purchase #5	$245.74	6.166%	$260.8923	$260.89	$260.90	$260.90
Purchase #6	$198.28	3.625%	$205.4677	$205.47	$205.45	$205.50
Purchase #7	$199.78	10.466%	$220.689	$220.69	$220.70	$220.70
7 purchase totals =	$1,151.52		$1,231.7412	$1,231.74	$1,231.75	$1,231.80