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	$94.39	5.576%	$99.6532	$99.65	$99.65	$99.70
Purchase #2	$134.94	5.233%	$142.0014	$142.00	$142.00	$142.00
Purchase #3	$81.76	5.533%	$86.2838	$86.28	$86.30	$86.30
Purchase #4	$219.47	4.236%	$228.7667	$228.77	$228.75	$228.80
Purchase #5	$32.96	8.520%	$35.7682	$35.77	$35.75	$35.80
Purchase #6	$53.39	11.739%	$59.6575	$59.66	$59.65	$59.70
Purchase #7	$46.48	4.752%	$48.6887	$48.69	$48.70	$48.70
7 purchase totals =	$663.39		$700.8195	$700.82	$700.80	$701.00