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	$91.64	13.511%	$104.0215	$104.02	$104.00	$104.00
Purchase #2	$247.31	3.656%	$256.3517	$256.35	$256.35	$256.40
Purchase #3	$58.34	10.222%	$64.3035	$64.30	$64.30	$64.30
Purchase #4	$59.86	6.548%	$63.7796	$63.78	$63.80	$63.80
Purchase #5	$191.45	13.563%	$217.4164	$217.42	$217.40	$217.40
Purchase #6	$193.49	12.663%	$217.9916	$217.99	$218.00	$218.00
Purchase #7	$240.76	13.128%	$272.367	$272.37	$272.35	$272.40
7 purchase totals =	$1,082.85		$1,196.2313	$1,196.23	$1,196.20	$1,196.30