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	$194.37	11.107%	$215.9587	$215.96	$215.95	$216.00
Purchase #2	$140.70	8.358%	$152.4597	$152.46	$152.45	$152.50
Purchase #3	$53.83	4.124%	$56.0499	$56.05	$56.05	$56.00
Purchase #4	$249.79	7.804%	$269.2836	$269.28	$269.30	$269.30
Purchase #5	$106.31	11.407%	$118.4368	$118.44	$118.45	$118.40
Purchase #6	$126.96	12.323%	$142.6053	$142.61	$142.60	$142.60
Purchase #7	$60.88	5.642%	$64.3148	$64.31	$64.30	$64.30
7 purchase totals =	$932.84		$1,019.1088	$1,019.11	$1,019.10	$1,019.10