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	$235.27	3.256%	$242.9304	$242.93	$242.95	$242.90
Purchase #2	$222.63	13.321%	$252.2865	$252.29	$252.30	$252.30
Purchase #3	$131.96	5.377%	$139.0555	$139.06	$139.05	$139.10
Purchase #4	$41.97	10.267%	$46.2791	$46.28	$46.30	$46.30
Purchase #5	$202.67	3.497%	$209.7574	$209.76	$209.75	$209.80
Purchase #6	$85.53	4.237%	$89.1539	$89.15	$89.15	$89.20
Purchase #7	$35.32	4.620%	$36.9518	$36.95	$36.95	$37.00
7 purchase totals =	$955.35		$1,016.4146	$1,016.42	$1,016.45	$1,016.60