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	$219.48	10.322%	$242.1347	$242.13	$242.15	$242.10
Purchase #2	$5.60	8.715%	$6.088	$6.09	$6.10	$6.10
Purchase #3	$85.93	5.811%	$90.9234	$90.92	$90.90	$90.90
Purchase #4	$93.50	13.736%	$106.3432	$106.34	$106.35	$106.30
Purchase #5	$95.88	13.852%	$109.1613	$109.16	$109.15	$109.20
Purchase #6	$231.69	11.456%	$258.2324	$258.23	$258.25	$258.20
Purchase #7	$234.80	3.321%	$242.5977	$242.60	$242.60	$242.60
7 purchase totals =	$966.88		$1,055.4807	$1,055.47	$1,055.50	$1,055.40