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	$100.35	5.389%	$105.7579	$105.76	$105.75	$105.80
Purchase #2	$184.47	13.777%	$209.8844	$209.88	$209.90	$209.90
Purchase #3	$226.28	13.177%	$256.0969	$256.10	$256.10	$256.10
Purchase #4	$62.56	9.467%	$68.4826	$68.48	$68.50	$68.50
Purchase #5	$97.52	13.243%	$110.4346	$110.43	$110.45	$110.40
Purchase #6	$197.46	11.358%	$219.8875	$219.89	$219.90	$219.90
Purchase #7	$85.58	7.334%	$91.8564	$91.86	$91.85	$91.90
7 purchase totals =	$954.22		$1,062.4003	$1,062.40	$1,062.45	$1,062.50