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	$152.33	11.360%	$169.6347	$169.63	$169.65	$169.60
Purchase #2	$237.39	9.761%	$260.5616	$260.56	$260.55	$260.60
Purchase #3	$224.30	4.168%	$233.6488	$233.65	$233.65	$233.60
Purchase #4	$96.27	6.211%	$102.2493	$102.25	$102.25	$102.20
Purchase #5	$54.86	7.770%	$59.1226	$59.12	$59.10	$59.10
Purchase #6	$221.26	11.674%	$247.0899	$247.09	$247.10	$247.10
Purchase #7	$98.94	6.859%	$105.7263	$105.73	$105.75	$105.70
7 purchase totals =	$1,085.35		$1,178.0332	$1,178.03	$1,178.05	$1,177.90