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	$93.50	9.470%	$102.3545	$102.35	$102.35	$102.40
Purchase #2	$10.83	8.506%	$11.7512	$11.75	$11.75	$11.80
Purchase #3	$37.58	9.513%	$41.155	$41.16	$41.15	$41.20
Purchase #4	$42.63	11.451%	$47.5116	$47.51	$47.50	$47.50
Purchase #5	$187.64	9.571%	$205.599	$205.60	$205.60	$205.60
Purchase #6	$55.42	6.655%	$59.1082	$59.11	$59.10	$59.10
Purchase #7	$174.63	12.223%	$195.975	$195.98	$196.00	$196.00
7 purchase totals =	$602.23		$663.4545	$663.46	$663.45	$663.60