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	$187.84	11.421%	$209.2932	$209.29	$209.30	$209.30
Purchase #2	$117.73	11.458%	$131.2195	$131.22	$131.20	$131.20
Purchase #3	$100.88	5.358%	$106.2852	$106.29	$106.30	$106.30
Purchase #4	$116.33	8.197%	$125.8656	$125.87	$125.85	$125.90
Purchase #5	$186.93	6.733%	$199.516	$199.52	$199.50	$199.50
Purchase #6	$114.47	9.112%	$124.9005	$124.90	$124.90	$124.90
Purchase #7	$204.60	4.731%	$214.2796	$214.28	$214.30	$214.30
7 purchase totals =	$1,028.78		$1,111.3596	$1,111.37	$1,111.35	$1,111.40