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	$146.87	3.522%	$152.0428	$152.04	$152.05	$152.00
Purchase #2	$231.41	5.860%	$244.9706	$244.97	$244.95	$245.00
Purchase #3	$40.68	13.189%	$46.0453	$46.05	$46.05	$46.00
Purchase #4	$40.40	4.758%	$42.3222	$42.32	$42.30	$42.30
Purchase #5	$66.40	7.499%	$71.3793	$71.38	$71.40	$71.40
Purchase #6	$248.78	3.107%	$256.5096	$256.51	$256.50	$256.50
Purchase #7	$77.53	5.800%	$82.0267	$82.03	$82.05	$82.00
7 purchase totals =	$852.07		$895.2965	$895.30	$895.30	$895.20