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	$53.87	9.662%	$59.0749	$59.07	$59.05	$59.10
Purchase #2	$10.41	6.836%	$11.1216	$11.12	$11.10	$11.10
Purchase #3	$133.38	10.554%	$147.4569	$147.46	$147.45	$147.50
Purchase #4	$59.46	13.240%	$67.3325	$67.33	$67.35	$67.30
Purchase #5	$209.75	4.365%	$218.9056	$218.91	$218.90	$218.90
Purchase #6	$197.72	9.607%	$216.715	$216.72	$216.70	$216.70
Purchase #7	$35.74	3.344%	$36.9351	$36.94	$36.95	$36.90
7 purchase totals =	$700.33		$757.5416	$757.55	$757.50	$757.50