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	$206.38	12.445%	$232.064	$232.06	$232.05	$232.10
Purchase #2	$164.70	4.749%	$172.5216	$172.52	$172.50	$172.50
Purchase #3	$160.64	8.793%	$174.7651	$174.77	$174.75	$174.80
Purchase #4	$90.64	6.331%	$96.3784	$96.38	$96.40	$96.40
Purchase #5	$141.45	12.617%	$159.2967	$159.30	$159.30	$159.30
Purchase #6	$93.32	7.611%	$100.4226	$100.42	$100.40	$100.40
Purchase #7	$189.33	9.544%	$207.3997	$207.40	$207.40	$207.40
7 purchase totals =	$1,046.46		$1,142.8481	$1,142.85	$1,142.80	$1,142.90