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	$223.33	4.347%	$233.0382	$233.04	$233.05	$233.00
Purchase #2	$229.44	3.833%	$238.2344	$238.23	$238.25	$238.20
Purchase #3	$75.57	7.614%	$81.3239	$81.32	$81.30	$81.30
Purchase #4	$236.25	5.300%	$248.7713	$248.77	$248.75	$248.80
Purchase #5	$147.39	3.735%	$152.895	$152.90	$152.90	$152.90
Purchase #6	$200.83	3.785%	$208.4314	$208.43	$208.45	$208.40
Purchase #7	$229.36	11.817%	$256.4635	$256.46	$256.45	$256.50
7 purchase totals =	$1,342.17		$1,419.1577	$1,419.15	$1,419.15	$1,419.10