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	$144.80	4.738%	$151.6606	$151.66	$151.65	$151.70
Purchase #2	$162.85	10.214%	$179.4835	$179.48	$179.50	$179.50
Purchase #3	$244.93	3.481%	$253.456	$253.46	$253.45	$253.50
Purchase #4	$248.40	7.365%	$266.6947	$266.69	$266.70	$266.70
Purchase #5	$233.82	10.694%	$258.8247	$258.82	$258.80	$258.80
Purchase #6	$245.82	11.151%	$273.2314	$273.23	$273.25	$273.20
Purchase #7	$129.80	11.630%	$144.8957	$144.90	$144.90	$144.90
7 purchase totals =	$1,410.42		$1,528.2466	$1,528.24	$1,528.25	$1,528.30