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	$92.56	3.589%	$95.882	$95.88	$95.90	$95.90
Purchase #2	$216.33	9.344%	$236.5439	$236.54	$236.55	$236.50
Purchase #3	$60.59	11.178%	$67.3628	$67.36	$67.35	$67.40
Purchase #4	$97.44	3.336%	$100.6906	$100.69	$100.70	$100.70
Purchase #5	$218.40	3.126%	$225.2272	$225.23	$225.25	$225.20
Purchase #6	$129.58	11.433%	$144.3949	$144.39	$144.40	$144.40
Purchase #7	$168.41	5.146%	$177.0764	$177.08	$177.10	$177.10
7 purchase totals =	$983.31		$1,047.1778	$1,047.17	$1,047.25	$1,047.20