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	$197.38	8.301%	$213.7645	$213.76	$213.75	$213.80
Purchase #2	$42.92	10.421%	$47.3927	$47.39	$47.40	$47.40
Purchase #3	$147.59	5.658%	$155.9406	$155.94	$155.95	$155.90
Purchase #4	$249.60	8.139%	$269.9149	$269.91	$269.90	$269.90
Purchase #5	$59.34	11.866%	$66.3813	$66.38	$66.40	$66.40
Purchase #6	$65.30	10.295%	$72.0226	$72.02	$72.00	$72.00
Purchase #7	$241.36	6.211%	$256.3509	$256.35	$256.35	$256.40
7 purchase totals =	$1,003.49		$1,081.7675	$1,081.75	$1,081.75	$1,081.80