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	$163.58	11.603%	$182.5602	$182.56	$182.55	$182.60
Purchase #2	$64.36	5.454%	$67.8702	$67.87	$67.85	$67.90
Purchase #3	$18.48	7.436%	$19.8542	$19.85	$19.85	$19.90
Purchase #4	$112.55	11.175%	$125.1275	$125.13	$125.15	$125.10
Purchase #5	$174.99	4.481%	$182.8313	$182.83	$182.85	$182.80
Purchase #6	$210.30	7.369%	$225.797	$225.80	$225.80	$225.80
Purchase #7	$200.95	7.240%	$215.4988	$215.50	$215.50	$215.50
7 purchase totals =	$945.21		$1,019.5392	$1,019.54	$1,019.55	$1,019.60