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	$56.72	3.326%	$58.6065	$58.61	$58.60	$58.60
Purchase #2	$101.81	3.813%	$105.692	$105.69	$105.70	$105.70
Purchase #3	$151.51	4.437%	$158.2325	$158.23	$158.25	$158.20
Purchase #4	$97.35	12.618%	$109.6336	$109.63	$109.65	$109.60
Purchase #5	$183.79	9.271%	$200.8292	$200.83	$200.85	$200.80
Purchase #6	$164.53	9.731%	$180.5404	$180.54	$180.55	$180.50
Purchase #7	$218.30	9.248%	$238.4884	$238.49	$238.50	$238.50
7 purchase totals =	$974.01		$1,052.0226	$1,052.02	$1,052.10	$1,051.90