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	$113.44	3.187%	$117.0553	$117.06	$117.05	$117.10
Purchase #2	$129.49	10.559%	$143.1628	$143.16	$143.15	$143.20
Purchase #3	$95.37	8.247%	$103.2352	$103.24	$103.25	$103.20
Purchase #4	$94.46	13.613%	$107.3188	$107.32	$107.30	$107.30
Purchase #5	$73.28	7.520%	$78.7907	$78.79	$78.80	$78.80
Purchase #6	$42.63	6.239%	$45.2897	$45.29	$45.30	$45.30
Purchase #7	$124.27	13.788%	$141.4043	$141.40	$141.40	$141.40
7 purchase totals =	$672.94		$736.2568	$736.26	$736.25	$736.30