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	$194.84	11.309%	$216.8745	$216.87	$216.85	$216.90
Purchase #2	$211.25	6.636%	$225.2686	$225.27	$225.25	$225.30
Purchase #3	$60.59	10.799%	$67.1331	$67.13	$67.15	$67.10
Purchase #4	$42.69	4.481%	$44.6029	$44.60	$44.60	$44.60
Purchase #5	$175.41	13.260%	$198.6694	$198.67	$198.65	$198.70
Purchase #6	$149.43	6.766%	$159.5404	$159.54	$159.55	$159.50
Purchase #7	$39.65	4.681%	$41.506	$41.51	$41.50	$41.50
7 purchase totals =	$873.86		$953.5949	$953.59	$953.55	$953.60