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	$145.36	11.525%	$162.1127	$162.11	$162.10	$162.10
Purchase #2	$101.59	10.291%	$112.0446	$112.04	$112.05	$112.00
Purchase #3	$42.55	5.207%	$44.7656	$44.77	$44.75	$44.80
Purchase #4	$159.77	5.465%	$168.5014	$168.50	$168.50	$168.50
Purchase #5	$216.65	8.222%	$234.463	$234.46	$234.45	$234.50
Purchase #6	$35.53	13.869%	$40.4577	$40.46	$40.45	$40.50
Purchase #7	$198.51	8.444%	$215.2722	$215.27	$215.25	$215.30
7 purchase totals =	$899.96		$977.6172	$977.61	$977.55	$977.70