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	$191.96	13.236%	$217.3678	$217.37	$217.35	$217.40
Purchase #2	$35.63	13.483%	$40.434	$40.43	$40.45	$40.40
Purchase #3	$69.84	3.733%	$72.4471	$72.45	$72.45	$72.40
Purchase #4	$149.89	11.620%	$167.3072	$167.31	$167.30	$167.30
Purchase #5	$51.63	5.781%	$54.6147	$54.61	$54.60	$54.60
Purchase #6	$179.53	13.846%	$204.3877	$204.39	$204.40	$204.40
Purchase #7	$219.30	4.872%	$229.9843	$229.98	$230.00	$230.00
7 purchase totals =	$897.78		$986.5428	$986.54	$986.55	$986.50