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	$197.99	7.535%	$212.9085	$212.91	$212.90	$212.90
Purchase #2	$83.85	8.199%	$90.7249	$90.72	$90.70	$90.70
Purchase #3	$198.37	12.208%	$222.587	$222.59	$222.60	$222.60
Purchase #4	$241.70	13.829%	$275.1247	$275.12	$275.10	$275.10
Purchase #5	$226.29	7.744%	$243.8139	$243.81	$243.80	$243.80
Purchase #6	$94.61	11.446%	$105.4391	$105.44	$105.45	$105.40
Purchase #7	$70.32	9.470%	$76.9793	$76.98	$77.00	$77.00
7 purchase totals =	$1,113.13		$1,227.5774	$1,227.57	$1,227.55	$1,227.50