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	$63.30	3.518%	$65.5269	$65.53	$65.55	$65.50
Purchase #2	$42.85	6.194%	$45.5041	$45.50	$45.50	$45.50
Purchase #3	$102.81	3.543%	$106.4526	$106.45	$106.45	$106.50
Purchase #4	$138.88	9.566%	$152.1653	$152.17	$152.15	$152.20
Purchase #5	$77.96	7.310%	$83.6589	$83.66	$83.65	$83.70
Purchase #6	$73.40	12.354%	$82.4678	$82.47	$82.45	$82.50
Purchase #7	$186.90	5.810%	$197.7589	$197.76	$197.75	$197.80
7 purchase totals =	$686.10		$733.5345	$733.54	$733.50	$733.70