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	$134.83	11.150%	$149.8635	$149.86	$149.85	$149.90
Purchase #2	$200.48	11.148%	$222.8295	$222.83	$222.85	$222.80
Purchase #3	$61.31	10.533%	$67.7678	$67.77	$67.75	$67.80
Purchase #4	$234.25	8.602%	$254.4002	$254.40	$254.40	$254.40
Purchase #5	$40.52	8.636%	$44.0193	$44.02	$44.00	$44.00
Purchase #6	$153.34	4.544%	$160.3078	$160.31	$160.30	$160.30
Purchase #7	$170.98	8.433%	$185.3987	$185.40	$185.40	$185.40
7 purchase totals =	$995.71		$1,084.5868	$1,084.59	$1,084.55	$1,084.60