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	$42.46	3.332%	$43.8748	$43.87	$43.85	$43.90
Purchase #2	$241.46	11.530%	$269.3003	$269.30	$269.30	$269.30
Purchase #3	$24.62	3.672%	$25.524	$25.52	$25.50	$25.50
Purchase #4	$151.64	4.738%	$158.8247	$158.82	$158.80	$158.80
Purchase #5	$194.81	3.133%	$200.9134	$200.91	$200.90	$200.90
Purchase #6	$86.48	11.460%	$96.3906	$96.39	$96.40	$96.40
Purchase #7	$191.40	13.651%	$217.528	$217.53	$217.55	$217.50
7 purchase totals =	$932.87		$1,012.3558	$1,012.34	$1,012.30	$1,012.30