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	$212.71	3.357%	$219.8507	$219.85	$219.85	$219.90
Purchase #2	$215.72	6.557%	$229.8648	$229.86	$229.85	$229.90
Purchase #3	$185.33	5.760%	$196.005	$196.01	$196.00	$196.00
Purchase #4	$170.39	3.739%	$176.7609	$176.76	$176.75	$176.80
Purchase #5	$249.98	11.295%	$278.2152	$278.22	$278.20	$278.20
Purchase #6	$229.71	10.817%	$254.5577	$254.56	$254.55	$254.60
Purchase #7	$124.47	4.345%	$129.8782	$129.88	$129.90	$129.90
7 purchase totals =	$1,388.31		$1,485.1325	$1,485.14	$1,485.10	$1,485.30