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	$176.69	10.447%	$195.1488	$195.15	$195.15	$195.10
Purchase #2	$36.37	6.818%	$38.8497	$38.85	$38.85	$38.80
Purchase #3	$192.59	6.645%	$205.3876	$205.39	$205.40	$205.40
Purchase #4	$221.61	13.278%	$251.0354	$251.04	$251.05	$251.00
Purchase #5	$130.92	11.811%	$146.383	$146.38	$146.40	$146.40
Purchase #6	$216.48	6.415%	$230.3672	$230.37	$230.35	$230.40
Purchase #7	$111.89	10.348%	$123.4684	$123.47	$123.45	$123.50
7 purchase totals =	$1,086.55		$1,190.6401	$1,190.65	$1,190.65	$1,190.60