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	$86.54	10.433%	$95.5687	$95.57	$95.55	$95.60
Purchase #2	$250.61	12.379%	$281.633	$281.63	$281.65	$281.60
Purchase #3	$169.98	9.590%	$186.2811	$186.28	$186.30	$186.30
Purchase #4	$236.80	11.248%	$263.4353	$263.44	$263.45	$263.40
Purchase #5	$172.64	10.763%	$191.2212	$191.22	$191.20	$191.20
Purchase #6	$204.42	8.629%	$222.0594	$222.06	$222.05	$222.10
Purchase #7	$55.55	8.451%	$60.2445	$60.24	$60.25	$60.20
7 purchase totals =	$1,176.54		$1,300.4432	$1,300.44	$1,300.45	$1,300.40