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	$189.96	10.189%	$209.315	$209.32	$209.30	$209.30
Purchase #2	$193.56	11.627%	$216.0652	$216.07	$216.05	$216.10
Purchase #3	$65.72	9.388%	$71.8898	$71.89	$71.90	$71.90
Purchase #4	$24.58	3.583%	$25.4607	$25.46	$25.45	$25.50
Purchase #5	$131.26	3.828%	$136.2846	$136.28	$136.30	$136.30
Purchase #6	$249.92	6.775%	$266.8521	$266.85	$266.85	$266.90
Purchase #7	$89.30	11.420%	$99.4981	$99.50	$99.50	$99.50
7 purchase totals =	$944.30		$1,025.3655	$1,025.37	$1,025.35	$1,025.50