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	$91.94	4.360%	$95.9486	$95.95	$95.95	$95.90
Purchase #2	$76.65	4.171%	$79.8471	$79.85	$79.85	$79.80
Purchase #3	$114.30	13.272%	$129.4699	$129.47	$129.45	$129.50
Purchase #4	$141.33	7.860%	$152.4385	$152.44	$152.45	$152.40
Purchase #5	$225.78	10.577%	$249.6608	$249.66	$249.65	$249.70
Purchase #6	$231.87	8.608%	$251.8294	$251.83	$251.85	$251.80
Purchase #7	$52.81	12.365%	$59.34	$59.34	$59.35	$59.30
7 purchase totals =	$934.68		$1,018.5343	$1,018.54	$1,018.55	$1,018.40