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	$164.65	5.289%	$173.3583	$173.36	$173.35	$173.40
Purchase #2	$89.73	12.635%	$101.0674	$101.07	$101.05	$101.10
Purchase #3	$149.76	4.426%	$156.3884	$156.39	$156.40	$156.40
Purchase #4	$208.90	11.559%	$233.0468	$233.05	$233.05	$233.00
Purchase #5	$177.62	6.597%	$189.3376	$189.34	$189.35	$189.30
Purchase #6	$233.89	10.507%	$258.4648	$258.46	$258.45	$258.50
Purchase #7	$242.75	3.331%	$250.836	$250.84	$250.85	$250.80
7 purchase totals =	$1,267.30		$1,362.4993	$1,362.51	$1,362.50	$1,362.50