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	$83.92	10.292%	$92.557	$92.56	$92.55	$92.60
Purchase #2	$35.64	6.378%	$37.9131	$37.91	$37.90	$37.90
Purchase #3	$179.56	6.632%	$191.4684	$191.47	$191.45	$191.50
Purchase #4	$90.31	13.203%	$102.2336	$102.23	$102.25	$102.20
Purchase #5	$156.47	10.762%	$173.3093	$173.31	$173.30	$173.30
Purchase #6	$48.60	10.664%	$53.7827	$53.78	$53.80	$53.80
Purchase #7	$91.39	13.534%	$103.7587	$103.76	$103.75	$103.80
7 purchase totals =	$685.89		$755.0228	$755.02	$755.00	$755.10