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	$139.93	8.631%	$152.0074	$152.01	$152.00	$152.00
Purchase #2	$136.27	11.761%	$152.2967	$152.30	$152.30	$152.30
Purchase #3	$118.87	8.223%	$128.6447	$128.64	$128.65	$128.60
Purchase #4	$55.88	9.358%	$61.1093	$61.11	$61.10	$61.10
Purchase #5	$105.78	11.174%	$117.5999	$117.60	$117.60	$117.60
Purchase #6	$204.75	8.169%	$221.476	$221.48	$221.50	$221.50
Purchase #7	$233.57	11.793%	$261.1149	$261.11	$261.10	$261.10
7 purchase totals =	$995.05		$1,094.2489	$1,094.25	$1,094.25	$1,094.20