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	$195.63	9.253%	$213.7316	$213.73	$213.75	$213.70
Purchase #2	$57.81	3.359%	$59.7518	$59.75	$59.75	$59.80
Purchase #3	$23.90	13.504%	$27.1275	$27.13	$27.15	$27.10
Purchase #4	$73.30	5.681%	$77.4642	$77.46	$77.45	$77.50
Purchase #5	$60.42	4.780%	$63.3081	$63.31	$63.30	$63.30
Purchase #6	$192.42	8.754%	$209.2644	$209.26	$209.25	$209.30
Purchase #7	$53.41	5.314%	$56.2482	$56.25	$56.25	$56.20
7 purchase totals =	$656.89		$706.8958	$706.89	$706.90	$706.90