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	$58.94	4.632%	$61.6701	$61.67	$61.65	$61.70
Purchase #2	$58.41	10.353%	$64.4572	$64.46	$64.45	$64.50
Purchase #3	$34.72	7.425%	$37.298	$37.30	$37.30	$37.30
Purchase #4	$179.27	11.831%	$200.4794	$200.48	$200.50	$200.50
Purchase #5	$96.56	13.275%	$109.3783	$109.38	$109.40	$109.40
Purchase #6	$45.69	12.839%	$51.5561	$51.56	$51.55	$51.60
Purchase #7	$157.43	13.593%	$178.8295	$178.83	$178.85	$178.80
7 purchase totals =	$631.02		$703.6686	$703.68	$703.70	$703.80