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	$130.56	11.719%	$145.8603	$145.86	$145.85	$145.90
Purchase #2	$124.98	4.646%	$130.7866	$130.79	$130.80	$130.80
Purchase #3	$89.54	7.350%	$96.1212	$96.12	$96.10	$96.10
Purchase #4	$96.91	9.547%	$106.162	$106.16	$106.15	$106.20
Purchase #5	$233.89	6.814%	$249.8273	$249.83	$249.85	$249.80
Purchase #6	$147.45	5.483%	$155.5347	$155.53	$155.55	$155.50
Purchase #7	$45.59	4.783%	$47.7706	$47.77	$47.75	$47.80
7 purchase totals =	$868.92		$932.0627	$932.06	$932.05	$932.10