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	$196.92	11.221%	$219.0164	$219.02	$219.00	$219.00
Purchase #2	$236.86	8.453%	$256.8818	$256.88	$256.90	$256.90
Purchase #3	$167.94	6.594%	$179.014	$179.01	$179.00	$179.00
Purchase #4	$198.92	10.187%	$219.184	$219.18	$219.20	$219.20
Purchase #5	$67.72	11.237%	$75.3297	$75.33	$75.35	$75.30
Purchase #6	$88.75	4.151%	$92.434	$92.43	$92.45	$92.40
Purchase #7	$243.49	10.690%	$269.5191	$269.52	$269.50	$269.50
7 purchase totals =	$1,200.60		$1,311.3790	$1,311.37	$1,311.40	$1,311.30