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	$88.90	7.535%	$95.5986	$95.60	$95.60	$95.60
Purchase #2	$215.29	7.341%	$231.0944	$231.09	$231.10	$231.10
Purchase #3	$92.33	5.772%	$97.6593	$97.66	$97.65	$97.70
Purchase #4	$191.59	13.173%	$216.8282	$216.83	$216.85	$216.80
Purchase #5	$117.69	11.550%	$131.2832	$131.28	$131.30	$131.30
Purchase #6	$156.26	4.257%	$162.912	$162.91	$162.90	$162.90
Purchase #7	$173.62	10.674%	$192.1522	$192.15	$192.15	$192.20
7 purchase totals =	$1,035.68		$1,127.5279	$1,127.52	$1,127.55	$1,127.60