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	$161.62	3.857%	$167.8537	$167.85	$167.85	$167.90
Purchase #2	$66.55	8.504%	$72.2094	$72.21	$72.20	$72.20
Purchase #3	$199.77	9.842%	$219.4314	$219.43	$219.45	$219.40
Purchase #4	$154.28	13.361%	$174.8934	$174.89	$174.90	$174.90
Purchase #5	$130.78	10.594%	$144.6348	$144.63	$144.65	$144.60
Purchase #6	$154.89	8.149%	$167.512	$167.51	$167.50	$167.50
Purchase #7	$68.34	7.485%	$73.4552	$73.46	$73.45	$73.50
7 purchase totals =	$936.23		$1,019.9899	$1,019.98	$1,020.00	$1,020.00