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	$196.26	13.319%	$222.3999	$222.40	$222.40	$222.40
Purchase #2	$229.92	11.435%	$256.2114	$256.21	$256.20	$256.20
Purchase #3	$111.54	11.517%	$124.3861	$124.39	$124.40	$124.40
Purchase #4	$120.80	3.492%	$125.0183	$125.02	$125.00	$125.00
Purchase #5	$244.59	4.288%	$255.078	$255.08	$255.10	$255.10
Purchase #6	$57.70	3.117%	$59.4985	$59.50	$59.50	$59.50
Purchase #7	$170.94	11.855%	$191.2049	$191.20	$191.20	$191.20
7 purchase totals =	$1,131.75		$1,233.7971	$1,233.80	$1,233.80	$1,233.80