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	$72.39	6.288%	$76.9419	$76.94	$76.95	$76.90
Purchase #2	$125.81	5.340%	$132.5283	$132.53	$132.55	$132.50
Purchase #3	$55.67	6.763%	$59.435	$59.44	$59.45	$59.40
Purchase #4	$49.28	10.606%	$54.5066	$54.51	$54.50	$54.50
Purchase #5	$112.87	13.748%	$128.3874	$128.39	$128.40	$128.40
Purchase #6	$191.29	4.413%	$199.7316	$199.73	$199.75	$199.70
Purchase #7	$218.82	10.334%	$241.4329	$241.43	$241.45	$241.40
7 purchase totals =	$826.13		$892.9637	$892.97	$893.05	$892.80