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	$114.49	13.803%	$130.2931	$130.29	$130.30	$130.30
Purchase #2	$211.98	7.300%	$227.4545	$227.45	$227.45	$227.50
Purchase #3	$117.29	8.156%	$126.8562	$126.86	$126.85	$126.90
Purchase #4	$31.37	5.360%	$33.0514	$33.05	$33.05	$33.10
Purchase #5	$206.43	3.796%	$214.2661	$214.27	$214.25	$214.30
Purchase #6	$153.73	8.450%	$166.7202	$166.72	$166.70	$166.70
Purchase #7	$178.72	10.173%	$196.9012	$196.90	$196.90	$196.90
7 purchase totals =	$1,014.01		$1,095.5427	$1,095.54	$1,095.50	$1,095.70