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	$66.99	8.771%	$72.8657	$72.87	$72.85	$72.90
Purchase #2	$188.66	3.833%	$195.8913	$195.89	$195.90	$195.90
Purchase #3	$185.56	8.241%	$200.852	$200.85	$200.85	$200.90
Purchase #4	$86.75	3.532%	$89.814	$89.81	$89.80	$89.80
Purchase #5	$186.58	13.643%	$212.0351	$212.04	$212.05	$212.00
Purchase #6	$130.29	8.833%	$141.7985	$141.80	$141.80	$141.80
Purchase #7	$216.37	13.590%	$245.7747	$245.77	$245.75	$245.80
7 purchase totals =	$1,061.20		$1,159.0313	$1,159.03	$1,159.00	$1,159.10