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	$174.72	5.443%	$184.23	$184.23	$184.25	$184.20
Purchase #2	$122.48	7.231%	$131.3365	$131.34	$131.35	$131.30
Purchase #3	$165.72	6.140%	$175.8952	$175.90	$175.90	$175.90
Purchase #4	$139.54	3.722%	$144.7337	$144.73	$144.75	$144.70
Purchase #5	$34.90	5.798%	$36.9235	$36.92	$36.90	$36.90
Purchase #6	$116.33	7.226%	$124.736	$124.74	$124.75	$124.70
Purchase #7	$198.93	3.129%	$205.1545	$205.15	$205.15	$205.20
7 purchase totals =	$952.62		$1,003.0094	$1,003.01	$1,003.05	$1,002.90