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	$76.52	7.526%	$82.2789	$82.28	$82.30	$82.30
Purchase #2	$37.50	7.484%	$40.3065	$40.31	$40.30	$40.30
Purchase #3	$180.66	4.246%	$188.3308	$188.33	$188.35	$188.30
Purchase #4	$221.54	7.321%	$237.7589	$237.76	$237.75	$237.80
Purchase #5	$155.54	13.740%	$176.9112	$176.91	$176.90	$176.90
Purchase #6	$175.97	7.772%	$189.6464	$189.65	$189.65	$189.60
Purchase #7	$129.27	12.748%	$145.7493	$145.75	$145.75	$145.70
7 purchase totals =	$977.00		$1,060.9820	$1,060.99	$1,061.00	$1,060.90