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	$227.41	9.532%	$249.0867	$249.09	$249.10	$249.10
Purchase #2	$88.85	13.635%	$100.9647	$100.96	$100.95	$101.00
Purchase #3	$104.87	6.731%	$111.9288	$111.93	$111.95	$111.90
Purchase #4	$65.34	10.341%	$72.0968	$72.10	$72.10	$72.10
Purchase #5	$215.63	12.431%	$242.435	$242.44	$242.45	$242.40
Purchase #6	$140.77	6.808%	$150.3536	$150.35	$150.35	$150.40
Purchase #7	$169.47	5.405%	$178.6299	$178.63	$178.65	$178.60
7 purchase totals =	$1,012.34		$1,105.4955	$1,105.50	$1,105.55	$1,105.50