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	$191.43	10.732%	$211.9743	$211.97	$211.95	$212.00
Purchase #2	$5.32	11.655%	$5.94	$5.94	$5.95	$5.90
Purchase #3	$191.32	6.244%	$203.266	$203.27	$203.25	$203.30
Purchase #4	$125.44	11.234%	$139.5319	$139.53	$139.55	$139.50
Purchase #5	$74.95	11.304%	$83.4223	$83.42	$83.40	$83.40
Purchase #6	$51.83	7.157%	$55.5395	$55.54	$55.55	$55.50
Purchase #7	$111.72	10.687%	$123.6595	$123.66	$123.65	$123.70
7 purchase totals =	$752.01		$823.3335	$823.33	$823.30	$823.30