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	$64.83	4.507%	$67.7519	$67.75	$67.75	$67.80
Purchase #2	$215.54	3.353%	$222.7671	$222.77	$222.75	$222.80
Purchase #3	$190.40	4.536%	$199.0365	$199.04	$199.05	$199.00
Purchase #4	$170.90	4.658%	$178.8605	$178.86	$178.85	$178.90
Purchase #5	$37.75	3.203%	$38.9591	$38.96	$38.95	$39.00
Purchase #6	$228.37	10.240%	$251.7551	$251.76	$251.75	$251.80
Purchase #7	$186.68	6.782%	$199.3406	$199.34	$199.35	$199.30
7 purchase totals =	$1,094.47		$1,158.4708	$1,158.48	$1,158.45	$1,158.60