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	$160.53	7.689%	$172.8732	$172.87	$172.85	$172.90
Purchase #2	$146.56	3.216%	$151.2734	$151.27	$151.25	$151.30
Purchase #3	$213.58	3.465%	$220.9805	$220.98	$221.00	$221.00
Purchase #4	$84.84	12.711%	$95.624	$95.62	$95.60	$95.60
Purchase #5	$48.98	11.341%	$54.5348	$54.53	$54.55	$54.50
Purchase #6	$197.62	3.741%	$205.013	$205.01	$205.00	$205.00
Purchase #7	$110.31	12.278%	$123.8539	$123.85	$123.85	$123.90
7 purchase totals =	$962.42		$1,024.1528	$1,024.13	$1,024.10	$1,024.20