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	$199.91	5.522%	$210.949	$210.95	$210.95	$210.90
Purchase #2	$114.32	11.204%	$127.1284	$127.13	$127.15	$127.10
Purchase #3	$104.33	11.789%	$116.6295	$116.63	$116.65	$116.60
Purchase #4	$130.63	10.547%	$144.4075	$144.41	$144.40	$144.40
Purchase #5	$208.98	6.301%	$222.1478	$222.15	$222.15	$222.10
Purchase #6	$163.84	6.624%	$174.6928	$174.69	$174.70	$174.70
Purchase #7	$14.48	12.503%	$16.2904	$16.29	$16.30	$16.30
7 purchase totals =	$936.49		$1,012.2454	$1,012.25	$1,012.30	$1,012.10