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	$190.68	13.250%	$215.9451	$215.95	$215.95	$215.90
Purchase #2	$238.86	10.382%	$263.6584	$263.66	$263.65	$263.70
Purchase #3	$93.53	7.597%	$100.6355	$100.64	$100.65	$100.60
Purchase #4	$162.89	5.220%	$171.3929	$171.39	$171.40	$171.40
Purchase #5	$226.39	13.289%	$256.475	$256.48	$256.50	$256.50
Purchase #6	$154.96	12.143%	$173.7768	$173.78	$173.80	$173.80
Purchase #7	$245.97	7.124%	$263.4929	$263.49	$263.50	$263.50
7 purchase totals =	$1,313.28		$1,445.3766	$1,445.39	$1,445.45	$1,445.40