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	$85.90	9.715%	$94.2452	$94.25	$94.25	$94.20
Purchase #2	$211.52	10.448%	$233.6196	$233.62	$233.60	$233.60
Purchase #3	$115.92	5.578%	$122.386	$122.39	$122.40	$122.40
Purchase #4	$179.75	6.570%	$191.5596	$191.56	$191.55	$191.60
Purchase #5	$131.34	6.107%	$139.3609	$139.36	$139.35	$139.40
Purchase #6	$179.31	9.451%	$196.2566	$196.26	$196.25	$196.30
Purchase #7	$136.86	11.450%	$152.5305	$152.53	$152.55	$152.50
7 purchase totals =	$1,040.60		$1,129.9584	$1,129.97	$1,129.95	$1,130.00