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	$167.57	13.397%	$190.0194	$190.02	$190.00	$190.00
Purchase #2	$65.30	9.632%	$71.5897	$71.59	$71.60	$71.60
Purchase #3	$5.67	10.306%	$6.2544	$6.25	$6.25	$6.30
Purchase #4	$118.83	12.474%	$133.6529	$133.65	$133.65	$133.70
Purchase #5	$9.79	10.166%	$10.7853	$10.79	$10.80	$10.80
Purchase #6	$11.45	9.521%	$12.5402	$12.54	$12.55	$12.50
Purchase #7	$33.78	12.210%	$37.9045	$37.90	$37.90	$37.90
7 purchase totals =	$412.39		$462.7464	$462.74	$462.75	$462.80