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	$189.56	10.483%	$209.4316	$209.43	$209.45	$209.40
Purchase #2	$182.77	11.490%	$203.7703	$203.77	$203.75	$203.80
Purchase #3	$78.44	4.780%	$82.1894	$82.19	$82.20	$82.20
Purchase #4	$198.41	4.612%	$207.5607	$207.56	$207.55	$207.60
Purchase #5	$180.38	9.147%	$196.8794	$196.88	$196.90	$196.90
Purchase #6	$10.53	8.482%	$11.4232	$11.42	$11.40	$11.40
Purchase #7	$145.62	3.450%	$150.6439	$150.64	$150.65	$150.60
7 purchase totals =	$985.71		$1,061.8985	$1,061.89	$1,061.90	$1,061.90