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	$187.60	5.623%	$198.1487	$198.15	$198.15	$198.10
Purchase #2	$7.83	13.148%	$8.8595	$8.86	$8.85	$8.90
Purchase #3	$72.65	11.303%	$80.8616	$80.86	$80.85	$80.90
Purchase #4	$161.49	12.606%	$181.8474	$181.85	$181.85	$181.80
Purchase #5	$183.76	8.629%	$199.6167	$199.62	$199.60	$199.60
Purchase #6	$193.61	3.624%	$200.6264	$200.63	$200.65	$200.60
Purchase #7	$175.80	6.123%	$186.5642	$186.56	$186.55	$186.60
7 purchase totals =	$982.74		$1,056.5245	$1,056.53	$1,056.50	$1,056.50