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	$86.66	11.872%	$96.9483	$96.95	$96.95	$96.90
Purchase #2	$26.32	3.546%	$27.2533	$27.25	$27.25	$27.30
Purchase #3	$231.83	8.489%	$251.51	$251.51	$251.50	$251.50
Purchase #4	$102.98	9.472%	$112.7343	$112.73	$112.75	$112.70
Purchase #5	$139.62	11.298%	$155.3943	$155.39	$155.40	$155.40
Purchase #6	$196.50	4.400%	$205.146	$205.15	$205.15	$205.10
Purchase #7	$231.86	4.748%	$242.8687	$242.87	$242.85	$242.90
7 purchase totals =	$1,015.77		$1,091.8549	$1,091.85	$1,091.85	$1,091.80