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	$188.96	4.725%	$197.8884	$197.89	$197.90	$197.90
Purchase #2	$135.57	6.690%	$144.6396	$144.64	$144.65	$144.60
Purchase #3	$84.68	5.257%	$89.1316	$89.13	$89.15	$89.10
Purchase #4	$145.25	4.215%	$151.3723	$151.37	$151.35	$151.40
Purchase #5	$66.27	6.358%	$70.4834	$70.48	$70.50	$70.50
Purchase #6	$190.64	12.650%	$214.756	$214.76	$214.75	$214.80
Purchase #7	$169.88	3.799%	$176.3337	$176.33	$176.35	$176.30
7 purchase totals =	$981.25		$1,044.6050	$1,044.60	$1,044.65	$1,044.60