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	$63.53	11.775%	$71.0107	$71.01	$71.00	$71.00
Purchase #2	$168.31	11.366%	$187.4401	$187.44	$187.45	$187.40
Purchase #3	$37.98	5.427%	$40.0412	$40.04	$40.05	$40.00
Purchase #4	$120.91	7.634%	$130.1403	$130.14	$130.15	$130.10
Purchase #5	$186.29	10.191%	$205.2748	$205.27	$205.25	$205.30
Purchase #6	$145.67	8.525%	$158.0884	$158.09	$158.10	$158.10
Purchase #7	$231.30	10.454%	$255.4801	$255.48	$255.50	$255.50
7 purchase totals =	$953.99		$1,047.4756	$1,047.47	$1,047.50	$1,047.40