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	$160.30	4.470%	$167.4654	$167.47	$167.45	$167.50
Purchase #2	$34.78	4.647%	$36.3962	$36.40	$36.40	$36.40
Purchase #3	$155.35	4.677%	$162.6157	$162.62	$162.60	$162.60
Purchase #4	$182.33	4.535%	$190.5987	$190.60	$190.60	$190.60
Purchase #5	$14.73	10.698%	$16.3058	$16.31	$16.30	$16.30
Purchase #6	$109.53	3.572%	$113.4424	$113.44	$113.45	$113.40
Purchase #7	$63.90	11.455%	$71.2197	$71.22	$71.20	$71.20
7 purchase totals =	$720.92		$758.0439	$758.06	$758.00	$758.00