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	$140.63	10.472%	$155.3568	$155.36	$155.35	$155.40
Purchase #2	$136.89	7.613%	$147.3114	$147.31	$147.30	$147.30
Purchase #3	$246.52	4.151%	$256.753	$256.75	$256.75	$256.80
Purchase #4	$57.30	3.775%	$59.4631	$59.46	$59.45	$59.50
Purchase #5	$151.58	7.227%	$162.5347	$162.53	$162.55	$162.50
Purchase #6	$130.89	11.162%	$145.4999	$145.50	$145.50	$145.50
Purchase #7	$230.53	13.507%	$261.6677	$261.67	$261.65	$261.70
7 purchase totals =	$1,094.34		$1,188.5866	$1,188.58	$1,188.55	$1,188.70