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	$41.33	4.655%	$43.2539	$43.25	$43.25	$43.30
Purchase #2	$197.55	10.159%	$217.6191	$217.62	$217.60	$217.60
Purchase #3	$5.56	3.507%	$5.755	$5.76	$5.75	$5.80
Purchase #4	$229.85	10.491%	$253.9636	$253.96	$253.95	$254.00
Purchase #5	$243.41	5.317%	$256.3521	$256.35	$256.35	$256.40
Purchase #6	$176.62	13.160%	$199.8632	$199.86	$199.85	$199.90
Purchase #7	$95.37	13.851%	$108.5797	$108.58	$108.60	$108.60
7 purchase totals =	$989.69		$1,085.3866	$1,085.38	$1,085.35	$1,085.60