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	$191.35	7.634%	$205.9577	$205.96	$205.95	$206.00
Purchase #2	$81.32	5.495%	$85.7885	$85.79	$85.80	$85.80
Purchase #3	$168.28	7.833%	$181.4614	$181.46	$181.45	$181.50
Purchase #4	$46.82	12.108%	$52.489	$52.49	$52.50	$52.50
Purchase #5	$7.49	5.539%	$7.9049	$7.90	$7.90	$7.90
Purchase #6	$130.85	11.629%	$146.0665	$146.07	$146.05	$146.10
Purchase #7	$115.64	6.457%	$123.1069	$123.11	$123.10	$123.10
7 purchase totals =	$741.75		$802.7749	$802.78	$802.75	$802.90