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	$52.47	12.399%	$58.9758	$58.98	$59.00	$59.00
Purchase #2	$202.38	11.537%	$225.7286	$225.73	$225.75	$225.70
Purchase #3	$34.30	4.693%	$35.9097	$35.91	$35.90	$35.90
Purchase #4	$108.95	3.770%	$113.0574	$113.06	$113.05	$113.10
Purchase #5	$113.45	4.391%	$118.4316	$118.43	$118.45	$118.40
Purchase #6	$185.68	7.514%	$199.632	$199.63	$199.65	$199.60
Purchase #7	$240.41	10.159%	$264.8333	$264.83	$264.85	$264.80
7 purchase totals =	$937.64		$1,016.5684	$1,016.57	$1,016.65	$1,016.50