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	$168.45	10.329%	$185.8492	$185.85	$185.85	$185.80
Purchase #2	$108.45	7.475%	$116.5566	$116.56	$116.55	$116.60
Purchase #3	$153.65	10.370%	$169.5835	$169.58	$169.60	$169.60
Purchase #4	$78.58	3.600%	$81.4089	$81.41	$81.40	$81.40
Purchase #5	$196.55	13.716%	$223.5088	$223.51	$223.50	$223.50
Purchase #6	$190.65	10.506%	$210.6797	$210.68	$210.70	$210.70
Purchase #7	$97.85	9.822%	$107.4608	$107.46	$107.45	$107.50
7 purchase totals =	$994.18		$1,095.0475	$1,095.05	$1,095.05	$1,095.10