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	$228.72	11.315%	$254.5997	$254.60	$254.60	$254.60
Purchase #2	$61.60	5.147%	$64.7706	$64.77	$64.75	$64.80
Purchase #3	$65.38	5.107%	$68.719	$68.72	$68.70	$68.70
Purchase #4	$228.87	11.564%	$255.3365	$255.34	$255.35	$255.30
Purchase #5	$131.56	7.147%	$140.9626	$140.96	$140.95	$141.00
Purchase #6	$69.89	9.108%	$76.2556	$76.26	$76.25	$76.30
Purchase #7	$156.65	4.842%	$164.235	$164.24	$164.25	$164.20
7 purchase totals =	$942.67		$1,024.8790	$1,024.89	$1,024.85	$1,024.90