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	$151.72	8.271%	$164.2688	$164.27	$164.25	$164.30
Purchase #2	$71.94	8.251%	$77.8758	$77.88	$77.90	$77.90
Purchase #3	$35.61	10.746%	$39.4367	$39.44	$39.45	$39.40
Purchase #4	$244.37	7.754%	$263.3184	$263.32	$263.30	$263.30
Purchase #5	$92.32	7.143%	$98.9144	$98.91	$98.90	$98.90
Purchase #6	$178.67	9.445%	$195.5454	$195.55	$195.55	$195.50
Purchase #7	$95.35	10.660%	$105.5143	$105.51	$105.50	$105.50
7 purchase totals =	$869.98		$944.8738	$944.88	$944.85	$944.80