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	$105.27	11.767%	$117.6571	$117.66	$117.65	$117.70
Purchase #2	$71.44	10.852%	$79.1927	$79.19	$79.20	$79.20
Purchase #3	$66.77	7.426%	$71.7283	$71.73	$71.75	$71.70
Purchase #4	$151.56	13.238%	$171.6235	$171.62	$171.60	$171.60
Purchase #5	$59.36	9.419%	$64.9511	$64.95	$64.95	$65.00
Purchase #6	$55.91	5.540%	$59.0074	$59.01	$59.00	$59.00
Purchase #7	$122.30	7.560%	$131.5459	$131.55	$131.55	$131.50
7 purchase totals =	$632.61		$695.7060	$695.71	$695.70	$695.70