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	$162.44	3.685%	$168.4259	$168.43	$168.45	$168.40
Purchase #2	$172.93	13.314%	$195.9539	$195.95	$195.95	$196.00
Purchase #3	$25.45	7.347%	$27.3198	$27.32	$27.30	$27.30
Purchase #4	$65.51	9.343%	$71.6306	$71.63	$71.65	$71.60
Purchase #5	$234.34	11.361%	$260.9634	$260.96	$260.95	$261.00
Purchase #6	$149.32	4.199%	$155.5899	$155.59	$155.60	$155.60
Purchase #7	$129.93	8.600%	$141.104	$141.10	$141.10	$141.10
7 purchase totals =	$939.92		$1,020.9875	$1,020.98	$1,021.00	$1,021.00