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	$87.34	9.402%	$95.5517	$95.55	$95.55	$95.60
Purchase #2	$175.90	7.231%	$188.6193	$188.62	$188.60	$188.60
Purchase #3	$151.73	10.506%	$167.6708	$167.67	$167.65	$167.70
Purchase #4	$153.31	12.236%	$172.069	$172.07	$172.05	$172.10
Purchase #5	$82.27	4.389%	$85.8808	$85.88	$85.90	$85.90
Purchase #6	$98.64	11.681%	$110.1621	$110.16	$110.15	$110.20
Purchase #7	$121.54	10.134%	$133.8569	$133.86	$133.85	$133.90
7 purchase totals =	$870.73		$953.8106	$953.81	$953.75	$954.00