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	$196.45	13.357%	$222.6898	$222.69	$222.70	$222.70
Purchase #2	$73.88	6.690%	$78.8226	$78.82	$78.80	$78.80
Purchase #3	$110.51	5.579%	$116.6754	$116.68	$116.70	$116.70
Purchase #4	$225.41	4.405%	$235.3393	$235.34	$235.35	$235.30
Purchase #5	$84.84	11.140%	$94.2912	$94.29	$94.30	$94.30
Purchase #6	$10.72	10.311%	$11.8253	$11.83	$11.85	$11.80
Purchase #7	$226.52	13.303%	$256.654	$256.65	$256.65	$256.70
7 purchase totals =	$928.33		$1,016.2976	$1,016.30	$1,016.35	$1,016.30