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	$190.43	8.365%	$206.3595	$206.36	$206.35	$206.40
Purchase #2	$247.53	3.678%	$256.6342	$256.63	$256.65	$256.60
Purchase #3	$82.69	13.420%	$93.787	$93.79	$93.80	$93.80
Purchase #4	$172.87	8.542%	$187.6366	$187.64	$187.65	$187.60
Purchase #5	$75.83	8.467%	$82.2505	$82.25	$82.25	$82.30
Purchase #6	$105.52	10.290%	$116.378	$116.38	$116.40	$116.40
Purchase #7	$209.89	13.790%	$238.8338	$238.83	$238.85	$238.80
7 purchase totals =	$1,084.76		$1,181.8796	$1,181.88	$1,181.95	$1,181.90