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	$112.73	4.253%	$117.5244	$117.52	$117.50	$117.50
Purchase #2	$63.57	5.404%	$67.0053	$67.01	$67.00	$67.00
Purchase #3	$88.82	6.749%	$94.8145	$94.81	$94.80	$94.80
Purchase #4	$36.43	4.653%	$38.1251	$38.13	$38.15	$38.10
Purchase #5	$233.93	9.479%	$256.1042	$256.10	$256.10	$256.10
Purchase #6	$241.93	3.604%	$250.6492	$250.65	$250.65	$250.60
Purchase #7	$172.65	4.287%	$180.0515	$180.05	$180.05	$180.10
7 purchase totals =	$950.06		$1,004.2742	$1,004.27	$1,004.25	$1,004.20