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	$90.85	7.801%	$97.9372	$97.94	$97.95	$97.90
Purchase #2	$159.52	3.455%	$165.0314	$165.03	$165.05	$165.00
Purchase #3	$243.78	3.266%	$251.7419	$251.74	$251.75	$251.70
Purchase #4	$189.69	3.786%	$196.8717	$196.87	$196.85	$196.90
Purchase #5	$174.79	7.138%	$187.2665	$187.27	$187.25	$187.30
Purchase #6	$237.51	4.760%	$248.8155	$248.82	$248.80	$248.80
Purchase #7	$175.54	5.356%	$184.9419	$184.94	$184.95	$184.90
7 purchase totals =	$1,271.68		$1,332.6061	$1,332.61	$1,332.60	$1,332.50