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	$147.52	10.372%	$162.8208	$162.82	$162.80	$162.80
Purchase #2	$15.75	4.118%	$16.3986	$16.40	$16.40	$16.40
Purchase #3	$23.32	3.322%	$24.0947	$24.09	$24.10	$24.10
Purchase #4	$85.31	4.503%	$89.1515	$89.15	$89.15	$89.20
Purchase #5	$87.64	11.263%	$97.5109	$97.51	$97.50	$97.50
Purchase #6	$26.25	12.265%	$29.4696	$29.47	$29.45	$29.50
Purchase #7	$83.80	10.843%	$92.8864	$92.89	$92.90	$92.90
7 purchase totals =	$469.59		$512.3325	$512.33	$512.30	$512.40