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	$94.58	7.684%	$101.8475	$101.85	$101.85	$101.80
Purchase #2	$193.60	11.700%	$216.2512	$216.25	$216.25	$216.30
Purchase #3	$44.87	12.534%	$50.494	$50.49	$50.50	$50.50
Purchase #4	$142.74	10.436%	$157.6363	$157.64	$157.65	$157.60
Purchase #5	$70.34	3.474%	$72.7836	$72.78	$72.80	$72.80
Purchase #6	$57.93	8.560%	$62.8888	$62.89	$62.90	$62.90
Purchase #7	$181.91	4.730%	$190.5143	$190.51	$190.50	$190.50
7 purchase totals =	$785.97		$852.4157	$852.41	$852.45	$852.40