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	$87.33	8.854%	$95.0622	$95.06	$95.05	$95.10
Purchase #2	$188.35	4.810%	$197.4096	$197.41	$197.40	$197.40
Purchase #3	$31.76	9.650%	$34.8248	$34.82	$34.80	$34.80
Purchase #4	$182.60	7.455%	$196.2128	$196.21	$196.20	$196.20
Purchase #5	$124.26	8.566%	$134.9041	$134.90	$134.90	$134.90
Purchase #6	$190.46	3.166%	$196.49	$196.49	$196.50	$196.50
Purchase #7	$147.84	7.570%	$159.0315	$159.03	$159.05	$159.00
7 purchase totals =	$952.60		$1,013.9350	$1,013.92	$1,013.90	$1,013.90