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	$91.75	4.493%	$95.8723	$95.87	$95.85	$95.90
Purchase #2	$180.66	8.468%	$195.9583	$195.96	$195.95	$196.00
Purchase #3	$50.40	8.310%	$54.5882	$54.59	$54.60	$54.60
Purchase #4	$65.27	10.653%	$72.2232	$72.22	$72.20	$72.20
Purchase #5	$185.52	3.405%	$191.837	$191.84	$191.85	$191.80
Purchase #6	$151.74	13.492%	$172.2128	$172.21	$172.20	$172.20
Purchase #7	$192.73	8.603%	$209.3106	$209.31	$209.30	$209.30
7 purchase totals =	$918.07		$992.0024	$992.00	$991.95	$992.00