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	$125.54	6.763%	$134.0303	$134.03	$134.05	$134.00
Purchase #2	$124.89	5.108%	$131.2694	$131.27	$131.25	$131.30
Purchase #3	$59.33	6.148%	$62.9776	$62.98	$63.00	$63.00
Purchase #4	$101.34	7.858%	$109.3033	$109.30	$109.30	$109.30
Purchase #5	$248.46	7.407%	$266.8634	$266.86	$266.85	$266.90
Purchase #6	$160.97	4.518%	$168.2426	$168.24	$168.25	$168.20
Purchase #7	$145.93	11.395%	$162.5587	$162.56	$162.55	$162.60
7 purchase totals =	$966.46		$1,035.2453	$1,035.24	$1,035.25	$1,035.30