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	$221.76	10.804%	$245.719	$245.72	$245.70	$245.70
Purchase #2	$72.55	13.490%	$82.337	$82.34	$82.35	$82.30
Purchase #3	$30.52	5.348%	$32.1522	$32.15	$32.15	$32.20
Purchase #4	$39.65	5.395%	$41.7891	$41.79	$41.80	$41.80
Purchase #5	$39.60	6.767%	$42.2797	$42.28	$42.30	$42.30
Purchase #6	$215.55	10.532%	$238.2517	$238.25	$238.25	$238.30
Purchase #7	$119.94	9.807%	$131.7025	$131.70	$131.70	$131.70
7 purchase totals =	$739.57		$814.2312	$814.23	$814.25	$814.30