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	$196.30	8.280%	$212.5536	$212.55	$212.55	$212.60
Purchase #2	$190.30	8.823%	$207.0902	$207.09	$207.10	$207.10
Purchase #3	$55.90	11.117%	$62.1144	$62.11	$62.10	$62.10
Purchase #4	$33.61	10.104%	$37.006	$37.01	$37.00	$37.00
Purchase #5	$93.44	7.112%	$100.0855	$100.09	$100.10	$100.10
Purchase #6	$57.47	11.619%	$64.1474	$64.15	$64.15	$64.10
Purchase #7	$25.32	12.751%	$28.5486	$28.55	$28.55	$28.50
7 purchase totals =	$652.34		$711.5457	$711.55	$711.55	$711.50