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	$141.90	3.691%	$147.1375	$147.14	$147.15	$147.10
Purchase #2	$148.45	4.777%	$155.5415	$155.54	$155.55	$155.50
Purchase #3	$26.80	3.228%	$27.6651	$27.67	$27.65	$27.70
Purchase #4	$182.49	6.387%	$194.1456	$194.15	$194.15	$194.10
Purchase #5	$239.98	6.802%	$256.3034	$256.30	$256.30	$256.30
Purchase #6	$97.33	3.478%	$100.7151	$100.72	$100.70	$100.70
Purchase #7	$187.78	6.259%	$199.5332	$199.53	$199.55	$199.50
7 purchase totals =	$1,024.73		$1,081.0414	$1,081.05	$1,081.05	$1,080.90