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	$226.93	7.626%	$244.2357	$244.24	$244.25	$244.20
Purchase #2	$113.91	5.654%	$120.3505	$120.35	$120.35	$120.40
Purchase #3	$220.45	5.208%	$231.931	$231.93	$231.95	$231.90
Purchase #4	$61.88	6.532%	$65.922	$65.92	$65.90	$65.90
Purchase #5	$141.64	4.745%	$148.3608	$148.36	$148.35	$148.40
Purchase #6	$172.72	12.407%	$194.1494	$194.15	$194.15	$194.10
Purchase #7	$38.30	11.706%	$42.7834	$42.78	$42.80	$42.80
7 purchase totals =	$975.83		$1,047.7328	$1,047.73	$1,047.75	$1,047.70