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	$181.57	7.384%	$194.9771	$194.98	$195.00	$195.00
Purchase #2	$30.46	7.119%	$32.6284	$32.63	$32.65	$32.60
Purchase #3	$5.57	9.772%	$6.1143	$6.11	$6.10	$6.10
Purchase #4	$119.74	9.839%	$131.5212	$131.52	$131.50	$131.50
Purchase #5	$84.90	6.861%	$90.725	$90.73	$90.75	$90.70
Purchase #6	$65.72	9.820%	$72.1737	$72.17	$72.15	$72.20
Purchase #7	$210.59	6.612%	$224.5142	$224.51	$224.50	$224.50
7 purchase totals =	$698.55		$752.6539	$752.65	$752.65	$752.60