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	$144.96	4.435%	$151.389	$151.39	$151.40	$151.40
Purchase #2	$187.49	5.119%	$197.0876	$197.09	$197.10	$197.10
Purchase #3	$39.26	6.736%	$41.9046	$41.90	$41.90	$41.90
Purchase #4	$151.35	6.432%	$161.0848	$161.08	$161.10	$161.10
Purchase #5	$222.48	9.522%	$243.6645	$243.66	$243.65	$243.70
Purchase #6	$204.47	6.300%	$217.3516	$217.35	$217.35	$217.40
Purchase #7	$103.36	7.705%	$111.3239	$111.32	$111.30	$111.30
7 purchase totals =	$1,053.37		$1,123.8060	$1,123.79	$1,123.80	$1,123.90