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	$140.47	5.777%	$148.585	$148.59	$148.60	$148.60
Purchase #2	$234.44	4.346%	$244.6288	$244.63	$244.65	$244.60
Purchase #3	$156.83	11.166%	$174.3416	$174.34	$174.35	$174.30
Purchase #4	$142.35	6.464%	$151.5515	$151.55	$151.55	$151.60
Purchase #5	$186.58	7.720%	$200.984	$200.98	$201.00	$201.00
Purchase #6	$164.51	4.487%	$171.8916	$171.89	$171.90	$171.90
Purchase #7	$99.92	3.573%	$103.4901	$103.49	$103.50	$103.50
7 purchase totals =	$1,125.10		$1,195.4726	$1,195.47	$1,195.55	$1,195.50