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	$212.74	4.770%	$222.8877	$222.89	$222.90	$222.90
Purchase #2	$10.94	5.165%	$11.5051	$11.51	$11.50	$11.50
Purchase #3	$115.32	12.592%	$129.8411	$129.84	$129.85	$129.80
Purchase #4	$171.67	11.791%	$191.9116	$191.91	$191.90	$191.90
Purchase #5	$229.98	7.822%	$247.969	$247.97	$247.95	$248.00
Purchase #6	$162.77	5.466%	$171.667	$171.67	$171.65	$171.70
Purchase #7	$200.44	10.843%	$222.1737	$222.17	$222.15	$222.20
7 purchase totals =	$1,103.86		$1,197.9552	$1,197.96	$1,197.90	$1,198.00