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	$148.84	7.735%	$160.3528	$160.35	$160.35	$160.40
Purchase #2	$100.42	7.872%	$108.3251	$108.33	$108.35	$108.30
Purchase #3	$11.28	5.285%	$11.8761	$11.88	$11.90	$11.90
Purchase #4	$193.79	11.179%	$215.4538	$215.45	$215.45	$215.50
Purchase #5	$128.90	13.176%	$145.8839	$145.88	$145.90	$145.90
Purchase #6	$89.93	5.214%	$94.619	$94.62	$94.60	$94.60
Purchase #7	$79.28	13.519%	$89.9979	$90.00	$90.00	$90.00
7 purchase totals =	$752.44		$826.5086	$826.51	$826.55	$826.60