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	$125.98	5.135%	$132.4491	$132.45	$132.45	$132.40
Purchase #2	$60.79	3.696%	$63.0368	$63.04	$63.05	$63.00
Purchase #3	$52.53	4.466%	$54.876	$54.88	$54.90	$54.90
Purchase #4	$106.34	10.427%	$117.4281	$117.43	$117.45	$117.40
Purchase #5	$109.38	4.433%	$114.2288	$114.23	$114.25	$114.20
Purchase #6	$83.93	7.736%	$90.4228	$90.42	$90.40	$90.40
Purchase #7	$115.75	3.806%	$120.1554	$120.16	$120.15	$120.20
7 purchase totals =	$654.70		$692.5970	$692.61	$692.65	$692.50