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	$245.85	3.612%	$254.7301	$254.73	$254.75	$254.70
Purchase #2	$227.98	13.785%	$259.407	$259.41	$259.40	$259.40
Purchase #3	$205.30	4.172%	$213.8651	$213.87	$213.85	$213.90
Purchase #4	$52.67	3.550%	$54.5398	$54.54	$54.55	$54.50
Purchase #5	$190.96	8.189%	$206.5977	$206.60	$206.60	$206.60
Purchase #6	$39.31	6.594%	$41.9021	$41.90	$41.90	$41.90
Purchase #7	$146.72	6.661%	$156.493	$156.49	$156.50	$156.50
7 purchase totals =	$1,108.79		$1,187.5348	$1,187.54	$1,187.55	$1,187.50