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	$132.53	7.192%	$142.0616	$142.06	$142.05	$142.10
Purchase #2	$202.39	13.251%	$229.2087	$229.21	$229.20	$229.20
Purchase #3	$172.89	13.499%	$196.2284	$196.23	$196.25	$196.20
Purchase #4	$108.88	4.350%	$113.6163	$113.62	$113.60	$113.60
Purchase #5	$129.80	12.483%	$146.0029	$146.00	$146.00	$146.00
Purchase #6	$140.50	5.521%	$148.257	$148.26	$148.25	$148.30
Purchase #7	$83.70	3.454%	$86.591	$86.59	$86.60	$86.60
7 purchase totals =	$970.69		$1,061.9659	$1,061.97	$1,061.95	$1,062.00