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	$244.32	7.391%	$262.3777	$262.38	$262.40	$262.40
Purchase #2	$152.70	12.731%	$172.1402	$172.14	$172.15	$172.10
Purchase #3	$94.63	11.622%	$105.6279	$105.63	$105.65	$105.60
Purchase #4	$60.69	7.181%	$65.0481	$65.05	$65.05	$65.00
Purchase #5	$225.50	11.417%	$251.2453	$251.25	$251.25	$251.20
Purchase #6	$6.49	6.844%	$6.9342	$6.93	$6.95	$6.90
Purchase #7	$188.27	6.397%	$200.3136	$200.31	$200.30	$200.30
7 purchase totals =	$972.60		$1,063.6870	$1,063.69	$1,063.75	$1,063.50