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	$200.34	11.551%	$223.4813	$223.48	$223.50	$223.50
Purchase #2	$93.42	9.495%	$102.2902	$102.29	$102.30	$102.30
Purchase #3	$95.98	9.539%	$105.1355	$105.14	$105.15	$105.10
Purchase #4	$34.70	7.757%	$37.3917	$37.39	$37.40	$37.40
Purchase #5	$58.63	7.862%	$63.2395	$63.24	$63.25	$63.20
Purchase #6	$235.57	7.588%	$253.4451	$253.45	$253.45	$253.40
Purchase #7	$245.73	7.249%	$263.543	$263.54	$263.55	$263.50
7 purchase totals =	$964.37		$1,048.5263	$1,048.53	$1,048.60	$1,048.40