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	$214.61	3.256%	$221.5977	$221.60	$221.60	$221.60
Purchase #2	$102.83	5.635%	$108.6245	$108.62	$108.60	$108.60
Purchase #3	$215.34	13.541%	$244.4992	$244.50	$244.50	$244.50
Purchase #4	$189.80	13.872%	$216.1291	$216.13	$216.15	$216.10
Purchase #5	$56.60	7.520%	$60.8563	$60.86	$60.85	$60.90
Purchase #6	$19.54	11.320%	$21.7519	$21.75	$21.75	$21.80
Purchase #7	$162.71	10.356%	$179.5602	$179.56	$179.55	$179.60
7 purchase totals =	$961.43		$1,053.0189	$1,053.02	$1,053.00	$1,053.10