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	$59.29	4.587%	$62.0096	$62.01	$62.00	$62.00
Purchase #2	$199.27	6.507%	$212.2365	$212.24	$212.25	$212.20
Purchase #3	$96.92	8.816%	$105.4645	$105.46	$105.45	$105.50
Purchase #4	$152.83	6.526%	$162.8037	$162.80	$162.80	$162.80
Purchase #5	$40.31	9.263%	$44.0439	$44.04	$44.05	$44.00
Purchase #6	$209.48	4.750%	$219.4303	$219.43	$219.45	$219.40
Purchase #7	$86.37	11.603%	$96.3915	$96.39	$96.40	$96.40
7 purchase totals =	$844.47		$902.3800	$902.37	$902.40	$902.30