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	$111.61	12.243%	$125.2744	$125.27	$125.25	$125.30
Purchase #2	$40.64	12.248%	$45.6176	$45.62	$45.60	$45.60
Purchase #3	$127.72	3.121%	$131.7061	$131.71	$131.70	$131.70
Purchase #4	$222.54	4.601%	$232.7791	$232.78	$232.80	$232.80
Purchase #5	$206.88	7.370%	$222.1271	$222.13	$222.15	$222.10
Purchase #6	$178.91	7.685%	$192.6592	$192.66	$192.65	$192.70
Purchase #7	$198.39	13.652%	$225.4742	$225.47	$225.45	$225.50
7 purchase totals =	$1,086.69		$1,175.6377	$1,175.64	$1,175.60	$1,175.70