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	$56.26	11.155%	$62.5358	$62.54	$62.55	$62.50
Purchase #2	$216.91	10.865%	$240.4773	$240.48	$240.50	$240.50
Purchase #3	$200.70	4.740%	$210.2132	$210.21	$210.20	$210.20
Purchase #4	$168.93	8.597%	$183.4529	$183.45	$183.45	$183.50
Purchase #5	$33.54	3.698%	$34.7803	$34.78	$34.80	$34.80
Purchase #6	$102.32	3.264%	$105.6597	$105.66	$105.65	$105.70
Purchase #7	$179.48	6.485%	$191.1193	$191.12	$191.10	$191.10
7 purchase totals =	$958.14		$1,028.2385	$1,028.24	$1,028.25	$1,028.30