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	$215.89	3.317%	$223.0511	$223.05	$223.05	$223.10
Purchase #2	$139.58	4.585%	$145.9797	$145.98	$146.00	$146.00
Purchase #3	$53.67	8.553%	$58.2604	$58.26	$58.25	$58.30
Purchase #4	$156.84	8.195%	$169.693	$169.69	$169.70	$169.70
Purchase #5	$96.34	3.671%	$99.8766	$99.88	$99.90	$99.90
Purchase #6	$234.67	11.204%	$260.9624	$260.96	$260.95	$261.00
Purchase #7	$164.88	11.264%	$183.4521	$183.45	$183.45	$183.50
7 purchase totals =	$1,061.87		$1,141.2753	$1,141.27	$1,141.30	$1,141.50