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	$182.65	7.131%	$195.6748	$195.67	$195.65	$195.70
Purchase #2	$66.89	6.815%	$71.4486	$71.45	$71.45	$71.40
Purchase #3	$89.39	10.553%	$98.8233	$98.82	$98.80	$98.80
Purchase #4	$71.64	9.552%	$78.4831	$78.48	$78.50	$78.50
Purchase #5	$82.87	8.349%	$89.7888	$89.79	$89.80	$89.80
Purchase #6	$30.57	9.462%	$33.4625	$33.46	$33.45	$33.50
Purchase #7	$243.53	8.649%	$264.5929	$264.59	$264.60	$264.60
7 purchase totals =	$767.54		$832.2740	$832.26	$832.25	$832.30