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	$59.72	4.580%	$62.4552	$62.46	$62.45	$62.50
Purchase #2	$191.68	4.495%	$200.296	$200.30	$200.30	$200.30
Purchase #3	$191.40	8.842%	$208.3236	$208.32	$208.30	$208.30
Purchase #4	$214.32	7.142%	$229.6267	$229.63	$229.65	$229.60
Purchase #5	$240.31	10.331%	$265.1364	$265.14	$265.15	$265.10
Purchase #6	$41.92	10.385%	$46.2734	$46.27	$46.25	$46.30
Purchase #7	$107.50	9.628%	$117.8501	$117.85	$117.85	$117.90
7 purchase totals =	$1,046.85		$1,129.9614	$1,129.97	$1,129.95	$1,130.00