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	$231.29	5.385%	$243.745	$243.75	$243.75	$243.70
Purchase #2	$90.82	5.597%	$95.9032	$95.90	$95.90	$95.90
Purchase #3	$126.94	3.512%	$131.3981	$131.40	$131.40	$131.40
Purchase #4	$12.26	3.581%	$12.699	$12.70	$12.70	$12.70
Purchase #5	$200.79	5.529%	$211.8917	$211.89	$211.90	$211.90
Purchase #6	$161.44	4.528%	$168.75	$168.75	$168.75	$168.80
Purchase #7	$218.57	6.607%	$233.0109	$233.01	$233.00	$233.00
7 purchase totals =	$1,042.11		$1,097.3979	$1,097.40	$1,097.40	$1,097.40