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	$190.56	4.314%	$198.7808	$198.78	$198.80	$198.80
Purchase #2	$54.47	13.185%	$61.6519	$61.65	$61.65	$61.70
Purchase #3	$126.76	12.597%	$142.728	$142.73	$142.75	$142.70
Purchase #4	$249.65	3.560%	$258.5375	$258.54	$258.55	$258.50
Purchase #5	$52.29	13.647%	$59.426	$59.43	$59.45	$59.40
Purchase #6	$210.27	12.557%	$236.6736	$236.67	$236.65	$236.70
Purchase #7	$223.38	13.242%	$252.96	$252.96	$252.95	$253.00
7 purchase totals =	$1,107.38		$1,210.7578	$1,210.76	$1,210.80	$1,210.80