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	$199.94	6.868%	$213.6719	$213.67	$213.65	$213.70
Purchase #2	$131.26	7.805%	$141.5048	$141.50	$141.50	$141.50
Purchase #3	$56.43	4.835%	$59.1584	$59.16	$59.15	$59.20
Purchase #4	$247.87	4.221%	$258.3326	$258.33	$258.35	$258.30
Purchase #5	$23.80	13.174%	$26.9354	$26.94	$26.95	$26.90
Purchase #6	$174.76	12.479%	$196.5683	$196.57	$196.55	$196.60
Purchase #7	$223.69	12.269%	$251.1345	$251.13	$251.15	$251.10
7 purchase totals =	$1,057.75		$1,147.3059	$1,147.30	$1,147.30	$1,147.30