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	$247.79	6.385%	$263.6114	$263.61	$263.60	$263.60
Purchase #2	$194.35	12.523%	$218.6885	$218.69	$218.70	$218.70
Purchase #3	$166.93	13.846%	$190.0431	$190.04	$190.05	$190.00
Purchase #4	$156.89	7.807%	$169.1384	$169.14	$169.15	$169.10
Purchase #5	$54.64	6.359%	$58.1146	$58.11	$58.10	$58.10
Purchase #6	$27.86	11.617%	$31.0965	$31.10	$31.10	$31.10
Purchase #7	$142.39	8.580%	$154.6071	$154.61	$154.60	$154.60
7 purchase totals =	$990.85		$1,085.2996	$1,085.30	$1,085.30	$1,085.20