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	$197.86	5.511%	$208.7641	$208.76	$208.75	$208.80
Purchase #2	$243.40	4.599%	$254.594	$254.59	$254.60	$254.60
Purchase #3	$229.59	12.712%	$258.7755	$258.78	$258.80	$258.80
Purchase #4	$192.28	4.418%	$200.7749	$200.77	$200.75	$200.80
Purchase #5	$131.72	11.102%	$146.3436	$146.34	$146.35	$146.30
Purchase #6	$190.98	8.111%	$206.4704	$206.47	$206.45	$206.50
Purchase #7	$148.79	7.219%	$159.5312	$159.53	$159.55	$159.50
7 purchase totals =	$1,334.62		$1,435.2537	$1,435.24	$1,435.25	$1,435.30