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	$226.52	5.410%	$238.7747	$238.77	$238.75	$238.80
Purchase #2	$45.56	5.107%	$47.8867	$47.89	$47.90	$47.90
Purchase #3	$39.49	3.269%	$40.7809	$40.78	$40.80	$40.80
Purchase #4	$219.82	6.672%	$234.4864	$234.49	$234.50	$234.50
Purchase #5	$199.43	11.378%	$222.1211	$222.12	$222.10	$222.10
Purchase #6	$52.87	13.253%	$59.8769	$59.88	$59.90	$59.90
Purchase #7	$208.96	7.239%	$224.0866	$224.09	$224.10	$224.10
7 purchase totals =	$992.65		$1,068.0133	$1,068.02	$1,068.05	$1,068.10