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	$209.77	4.117%	$218.4062	$218.41	$218.40	$218.40
Purchase #2	$135.46	8.168%	$146.5244	$146.52	$146.50	$146.50
Purchase #3	$171.36	5.137%	$180.1628	$180.16	$180.15	$180.20
Purchase #4	$95.53	11.136%	$106.1682	$106.17	$106.15	$106.20
Purchase #5	$66.94	6.821%	$71.506	$71.51	$71.50	$71.50
Purchase #6	$211.59	6.792%	$225.9612	$225.96	$225.95	$226.00
Purchase #7	$216.38	7.833%	$233.329	$233.33	$233.35	$233.30
7 purchase totals =	$1,107.03		$1,182.0578	$1,182.06	$1,182.00	$1,182.10