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	$45.51	4.629%	$47.6167	$47.62	$47.60	$47.60
Purchase #2	$26.70	4.666%	$27.9458	$27.95	$27.95	$27.90
Purchase #3	$172.46	12.668%	$194.3072	$194.31	$194.30	$194.30
Purchase #4	$95.36	4.289%	$99.45	$99.45	$99.45	$99.50
Purchase #5	$72.50	11.154%	$80.5867	$80.59	$80.60	$80.60
Purchase #6	$51.60	6.453%	$54.9297	$54.93	$54.95	$54.90
Purchase #7	$226.33	10.226%	$249.4745	$249.47	$249.45	$249.50
7 purchase totals =	$690.46		$754.3106	$754.32	$754.30	$754.30