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	$114.54	9.460%	$125.3755	$125.38	$125.40	$125.40
Purchase #2	$68.31	6.321%	$72.6279	$72.63	$72.65	$72.60
Purchase #3	$79.76	4.394%	$83.2647	$83.26	$83.25	$83.30
Purchase #4	$150.54	8.145%	$162.8015	$162.80	$162.80	$162.80
Purchase #5	$152.72	12.410%	$171.6726	$171.67	$171.65	$171.70
Purchase #6	$18.49	4.414%	$19.3061	$19.31	$19.30	$19.30
Purchase #7	$188.75	6.198%	$200.4487	$200.45	$200.45	$200.40
7 purchase totals =	$773.11		$835.4970	$835.50	$835.50	$835.50