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	$162.49	8.281%	$175.9458	$175.95	$175.95	$175.90
Purchase #2	$37.57	8.564%	$40.7875	$40.79	$40.80	$40.80
Purchase #3	$54.53	9.224%	$59.5598	$59.56	$59.55	$59.60
Purchase #4	$104.30	9.599%	$114.3118	$114.31	$114.30	$114.30
Purchase #5	$90.98	10.806%	$100.8113	$100.81	$100.80	$100.80
Purchase #6	$81.92	11.267%	$91.1499	$91.15	$91.15	$91.10
Purchase #7	$144.84	5.137%	$152.2804	$152.28	$152.30	$152.30
7 purchase totals =	$676.63		$734.8465	$734.85	$734.85	$734.80