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	$192.41	11.484%	$214.5064	$214.51	$214.50	$214.50
Purchase #2	$67.93	5.639%	$71.7606	$71.76	$71.75	$71.80
Purchase #3	$134.91	12.674%	$152.0085	$152.01	$152.00	$152.00
Purchase #4	$180.69	7.256%	$193.8009	$193.80	$193.80	$193.80
Purchase #5	$100.56	4.727%	$105.3135	$105.31	$105.30	$105.30
Purchase #6	$140.72	13.447%	$159.6426	$159.64	$159.65	$159.60
Purchase #7	$49.60	3.675%	$51.4228	$51.42	$51.40	$51.40
7 purchase totals =	$866.82		$948.4553	$948.45	$948.40	$948.40