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	$59.53	4.460%	$62.185	$62.19	$62.20	$62.20
Purchase #2	$207.29	4.433%	$216.4792	$216.48	$216.50	$216.50
Purchase #3	$76.30	12.243%	$85.6414	$85.64	$85.65	$85.60
Purchase #4	$115.28	8.392%	$124.9543	$124.95	$124.95	$125.00
Purchase #5	$205.87	11.664%	$229.8827	$229.88	$229.90	$229.90
Purchase #6	$102.66	6.574%	$109.4089	$109.41	$109.40	$109.40
Purchase #7	$242.35	5.298%	$255.1897	$255.19	$255.20	$255.20
7 purchase totals =	$1,009.28		$1,083.7412	$1,083.74	$1,083.80	$1,083.80