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	$155.84	11.864%	$174.3289	$174.33	$174.35	$174.30
Purchase #2	$149.82	8.470%	$162.5098	$162.51	$162.50	$162.50
Purchase #3	$51.92	5.490%	$54.7704	$54.77	$54.75	$54.80
Purchase #4	$24.48	4.667%	$25.6225	$25.62	$25.60	$25.60
Purchase #5	$62.56	11.695%	$69.8764	$69.88	$69.90	$69.90
Purchase #6	$122.85	11.753%	$137.2886	$137.29	$137.30	$137.30
Purchase #7	$103.38	5.487%	$109.0525	$109.05	$109.05	$109.10
7 purchase totals =	$670.85		$733.4491	$733.45	$733.45	$733.50