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	$152.74	6.677%	$162.9384	$162.94	$162.95	$162.90
Purchase #2	$181.61	5.162%	$190.9847	$190.98	$191.00	$191.00
Purchase #3	$7.37	3.722%	$7.6443	$7.64	$7.65	$7.60
Purchase #4	$95.94	4.571%	$100.3254	$100.33	$100.35	$100.30
Purchase #5	$13.65	5.168%	$14.3554	$14.36	$14.35	$14.40
Purchase #6	$83.74	13.734%	$95.2409	$95.24	$95.25	$95.20
Purchase #7	$93.56	11.436%	$104.2595	$104.26	$104.25	$104.30
7 purchase totals =	$628.61		$675.7486	$675.75	$675.80	$675.70