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	$157.56	11.504%	$175.6857	$175.69	$175.70	$175.70
Purchase #2	$12.52	11.489%	$13.9584	$13.96	$13.95	$14.00
Purchase #3	$33.31	12.110%	$37.3438	$37.34	$37.35	$37.30
Purchase #4	$100.98	13.572%	$114.685	$114.69	$114.70	$114.70
Purchase #5	$45.86	9.290%	$50.1204	$50.12	$50.10	$50.10
Purchase #6	$215.87	10.344%	$238.1996	$238.20	$238.20	$238.20
Purchase #7	$40.31	5.269%	$42.4339	$42.43	$42.45	$42.40
7 purchase totals =	$606.41		$672.4268	$672.43	$672.45	$672.40