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	$91.71	5.151%	$96.434	$96.43	$96.45	$96.40
Purchase #2	$46.90	6.763%	$50.0718	$50.07	$50.05	$50.10
Purchase #3	$151.82	13.146%	$171.7783	$171.78	$171.80	$171.80
Purchase #4	$227.37	11.827%	$254.261	$254.26	$254.25	$254.30
Purchase #5	$183.47	4.365%	$191.4785	$191.48	$191.50	$191.50
Purchase #6	$209.97	4.640%	$219.7126	$219.71	$219.70	$219.70
Purchase #7	$110.71	5.522%	$116.8234	$116.82	$116.80	$116.80
7 purchase totals =	$1,021.95		$1,100.5596	$1,100.55	$1,100.55	$1,100.60