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	$58.74	5.236%	$61.8156	$61.82	$61.80	$61.80
Purchase #2	$7.61	4.380%	$7.9433	$7.94	$7.95	$7.90
Purchase #3	$182.94	5.357%	$192.7401	$192.74	$192.75	$192.70
Purchase #4	$141.36	5.325%	$148.8874	$148.89	$148.90	$148.90
Purchase #5	$208.41	11.110%	$231.5644	$231.56	$231.55	$231.60
Purchase #6	$246.63	10.161%	$271.6901	$271.69	$271.70	$271.70
Purchase #7	$242.70	5.160%	$255.2233	$255.22	$255.20	$255.20
7 purchase totals =	$1,088.39		$1,169.8642	$1,169.86	$1,169.85	$1,169.80