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	$180.47	10.734%	$199.8416	$199.84	$199.85	$199.80
Purchase #2	$87.78	4.784%	$91.9794	$91.98	$92.00	$92.00
Purchase #3	$19.66	9.344%	$21.497	$21.50	$21.50	$21.50
Purchase #4	$155.65	4.345%	$162.413	$162.41	$162.40	$162.40
Purchase #5	$80.93	4.829%	$84.8381	$84.84	$84.85	$84.80
Purchase #6	$86.77	4.675%	$90.8265	$90.83	$90.85	$90.80
Purchase #7	$196.68	10.385%	$217.1052	$217.11	$217.10	$217.10
7 purchase totals =	$807.94		$868.5008	$868.51	$868.55	$868.40