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	$90.80	5.593%	$95.8784	$95.88	$95.90	$95.90
Purchase #2	$16.65	10.703%	$18.432	$18.43	$18.45	$18.40
Purchase #3	$88.82	10.803%	$98.4152	$98.42	$98.40	$98.40
Purchase #4	$222.31	13.216%	$251.6905	$251.69	$251.70	$251.70
Purchase #5	$156.45	5.666%	$165.3145	$165.31	$165.30	$165.30
Purchase #6	$64.25	11.491%	$71.633	$71.63	$71.65	$71.60
Purchase #7	$47.30	13.431%	$53.6529	$53.65	$53.65	$53.70
7 purchase totals =	$686.58		$755.0165	$755.01	$755.05	$755.00