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	$88.51	7.659%	$95.289	$95.29	$95.30	$95.30
Purchase #2	$131.76	7.392%	$141.4997	$141.50	$141.50	$141.50
Purchase #3	$238.98	10.348%	$263.7097	$263.71	$263.70	$263.70
Purchase #4	$122.32	7.591%	$131.6053	$131.61	$131.60	$131.60
Purchase #5	$215.67	6.557%	$229.8115	$229.81	$229.80	$229.80
Purchase #6	$208.87	7.781%	$225.1222	$225.12	$225.10	$225.10
Purchase #7	$200.49	5.667%	$211.8518	$211.85	$211.85	$211.90
7 purchase totals =	$1,206.60		$1,298.8892	$1,298.89	$1,298.85	$1,298.90