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	$65.32	11.690%	$72.9559	$72.96	$72.95	$73.00
Purchase #2	$66.27	8.112%	$71.6458	$71.65	$71.65	$71.60
Purchase #3	$139.96	5.511%	$147.6732	$147.67	$147.65	$147.70
Purchase #4	$114.97	13.202%	$130.1483	$130.15	$130.15	$130.10
Purchase #5	$85.80	4.627%	$89.77	$89.77	$89.75	$89.80
Purchase #6	$213.58	3.778%	$221.6491	$221.65	$221.65	$221.60
Purchase #7	$50.80	5.235%	$53.4594	$53.46	$53.45	$53.50
7 purchase totals =	$736.70		$787.3017	$787.31	$787.25	$787.30