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	$211.91	10.663%	$234.506	$234.51	$234.50	$234.50
Purchase #2	$21.91	13.610%	$24.892	$24.89	$24.90	$24.90
Purchase #3	$79.77	13.235%	$90.3276	$90.33	$90.35	$90.30
Purchase #4	$145.33	6.464%	$154.7241	$154.72	$154.70	$154.70
Purchase #5	$140.62	10.484%	$155.3626	$155.36	$155.35	$155.40
Purchase #6	$79.94	13.229%	$90.5153	$90.52	$90.50	$90.50
Purchase #7	$7.71	10.512%	$8.5205	$8.52	$8.50	$8.50
7 purchase totals =	$687.19		$758.8481	$758.85	$758.80	$758.80