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	$195.79	8.238%	$211.9192	$211.92	$211.90	$211.90
Purchase #2	$215.64	11.723%	$240.9195	$240.92	$240.90	$240.90
Purchase #3	$52.48	8.182%	$56.7739	$56.77	$56.75	$56.80
Purchase #4	$104.84	6.324%	$111.4701	$111.47	$111.45	$111.50
Purchase #5	$35.63	3.432%	$36.8528	$36.85	$36.85	$36.90
Purchase #6	$191.78	13.765%	$218.1785	$218.18	$218.20	$218.20
Purchase #7	$148.73	9.183%	$162.3879	$162.39	$162.40	$162.40
7 purchase totals =	$944.89		$1,038.5019	$1,038.50	$1,038.45	$1,038.60