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	$195.46	5.116%	$205.4597	$205.46	$205.45	$205.50
Purchase #2	$91.45	8.842%	$99.536	$99.54	$99.55	$99.50
Purchase #3	$167.83	13.756%	$190.9167	$190.92	$190.90	$190.90
Purchase #4	$48.59	11.707%	$54.2784	$54.28	$54.30	$54.30
Purchase #5	$118.98	13.749%	$135.3386	$135.34	$135.35	$135.30
Purchase #6	$229.57	11.586%	$256.168	$256.17	$256.15	$256.20
Purchase #7	$35.55	11.811%	$39.7488	$39.75	$39.75	$39.70
7 purchase totals =	$887.43		$981.4462	$981.46	$981.45	$981.40