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	$49.66	7.230%	$53.2504	$53.25	$53.25	$53.30
Purchase #2	$6.33	11.738%	$7.073	$7.07	$7.05	$7.10
Purchase #3	$221.26	12.426%	$248.7538	$248.75	$248.75	$248.80
Purchase #4	$190.54	7.811%	$205.4231	$205.42	$205.40	$205.40
Purchase #5	$136.82	11.697%	$152.8238	$152.82	$152.80	$152.80
Purchase #6	$240.95	6.548%	$256.7274	$256.73	$256.75	$256.70
Purchase #7	$68.95	12.523%	$77.5846	$77.58	$77.60	$77.60
7 purchase totals =	$914.51		$1,001.6361	$1,001.62	$1,001.60	$1,001.70