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	$206.75	7.785%	$222.8455	$222.85	$222.85	$222.80
Purchase #2	$216.37	5.291%	$227.8181	$227.82	$227.80	$227.80
Purchase #3	$40.35	7.439%	$43.3516	$43.35	$43.35	$43.40
Purchase #4	$165.80	3.595%	$171.7605	$171.76	$171.75	$171.80
Purchase #5	$110.54	3.407%	$114.3061	$114.31	$114.30	$114.30
Purchase #6	$187.49	6.873%	$200.3762	$200.38	$200.40	$200.40
Purchase #7	$165.47	13.780%	$188.2718	$188.27	$188.25	$188.30
7 purchase totals =	$1,092.77		$1,168.7298	$1,168.74	$1,168.70	$1,168.80