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	$96.66	8.623%	$104.995	$105.00	$105.00	$105.00
Purchase #2	$171.41	11.166%	$190.5496	$190.55	$190.55	$190.50
Purchase #3	$247.46	10.490%	$273.4186	$273.42	$273.40	$273.40
Purchase #4	$154.41	11.462%	$172.1085	$172.11	$172.10	$172.10
Purchase #5	$209.86	5.623%	$221.6604	$221.66	$221.65	$221.70
Purchase #6	$105.27	5.213%	$110.7577	$110.76	$110.75	$110.80
Purchase #7	$94.29	5.641%	$99.6089	$99.61	$99.60	$99.60
7 purchase totals =	$1,079.36		$1,173.0987	$1,173.11	$1,173.05	$1,173.10