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	$214.80	10.750%	$237.891	$237.89	$237.90	$237.90
Purchase #2	$154.33	7.243%	$165.5081	$165.51	$165.50	$165.50
Purchase #3	$234.34	12.772%	$264.2699	$264.27	$264.25	$264.30
Purchase #4	$108.39	3.704%	$112.4048	$112.40	$112.40	$112.40
Purchase #5	$135.94	11.348%	$151.3665	$151.37	$151.35	$151.40
Purchase #6	$113.80	11.350%	$126.7163	$126.72	$126.70	$126.70
Purchase #7	$78.41	13.742%	$89.1851	$89.19	$89.20	$89.20
7 purchase totals =	$1,040.01		$1,147.3417	$1,147.35	$1,147.30	$1,147.40