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	$57.87	11.645%	$64.609	$64.61	$64.60	$64.60
Purchase #2	$53.95	12.137%	$60.4979	$60.50	$60.50	$60.50
Purchase #3	$99.62	5.598%	$105.1967	$105.20	$105.20	$105.20
Purchase #4	$102.33	5.107%	$107.556	$107.56	$107.55	$107.60
Purchase #5	$54.52	9.203%	$59.5375	$59.54	$59.55	$59.50
Purchase #6	$209.89	6.667%	$223.8834	$223.88	$223.90	$223.90
Purchase #7	$124.79	12.797%	$140.7594	$140.76	$140.75	$140.80
7 purchase totals =	$702.97		$762.0399	$762.05	$762.05	$762.10