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	$136.87	11.158%	$152.142	$152.14	$152.15	$152.10
Purchase #2	$22.80	13.572%	$25.8944	$25.89	$25.90	$25.90
Purchase #3	$198.97	5.550%	$210.0128	$210.01	$210.00	$210.00
Purchase #4	$190.41	5.259%	$200.4237	$200.42	$200.40	$200.40
Purchase #5	$188.91	6.107%	$200.4467	$200.45	$200.45	$200.40
Purchase #6	$92.64	12.316%	$104.0495	$104.05	$104.05	$104.00
Purchase #7	$117.99	10.685%	$130.5972	$130.60	$130.60	$130.60
7 purchase totals =	$948.59		$1,023.5663	$1,023.56	$1,023.55	$1,023.40