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	$88.81	7.688%	$95.6377	$95.64	$95.65	$95.60
Purchase #2	$164.84	11.865%	$184.3983	$184.40	$184.40	$184.40
Purchase #3	$235.94	8.322%	$255.5749	$255.57	$255.55	$255.60
Purchase #4	$121.37	8.451%	$131.627	$131.63	$131.65	$131.60
Purchase #5	$18.29	11.246%	$20.3469	$20.35	$20.35	$20.30
Purchase #6	$207.69	10.507%	$229.512	$229.51	$229.50	$229.50
Purchase #7	$100.31	8.117%	$108.4522	$108.45	$108.45	$108.50
7 purchase totals =	$937.25		$1,025.5490	$1,025.55	$1,025.55	$1,025.50