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	$12.71	10.609%	$14.0584	$14.06	$14.05	$14.10
Purchase #2	$246.29	5.532%	$259.9148	$259.91	$259.90	$259.90
Purchase #3	$141.84	7.609%	$152.6326	$152.63	$152.65	$152.60
Purchase #4	$97.56	11.223%	$108.5092	$108.51	$108.50	$108.50
Purchase #5	$148.53	4.467%	$155.1648	$155.16	$155.15	$155.20
Purchase #6	$145.80	3.146%	$150.3869	$150.39	$150.40	$150.40
Purchase #7	$92.64	10.616%	$102.4747	$102.47	$102.45	$102.50
7 purchase totals =	$885.37		$943.1414	$943.13	$943.10	$943.20