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	$242.25	9.402%	$265.0263	$265.03	$265.05	$265.00
Purchase #2	$209.95	11.472%	$234.0355	$234.04	$234.05	$234.00
Purchase #3	$204.61	8.245%	$221.4801	$221.48	$221.50	$221.50
Purchase #4	$192.47	11.846%	$215.27	$215.27	$215.25	$215.30
Purchase #5	$29.55	10.132%	$32.544	$32.54	$32.55	$32.50
Purchase #6	$18.31	13.387%	$20.7612	$20.76	$20.75	$20.80
Purchase #7	$28.85	5.374%	$30.4004	$30.40	$30.40	$30.40
7 purchase totals =	$925.99		$1,019.5175	$1,019.52	$1,019.55	$1,019.50