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	$224.65	12.355%	$252.4055	$252.41	$252.40	$252.40
Purchase #2	$18.56	12.626%	$20.9034	$20.90	$20.90	$20.90
Purchase #3	$175.57	11.813%	$196.3101	$196.31	$196.30	$196.30
Purchase #4	$233.74	3.333%	$241.5306	$241.53	$241.55	$241.50
Purchase #5	$76.74	11.459%	$85.5336	$85.53	$85.55	$85.50
Purchase #6	$156.39	9.462%	$171.1876	$171.19	$171.20	$171.20
Purchase #7	$89.98	5.199%	$94.6581	$94.66	$94.65	$94.70
7 purchase totals =	$975.63		$1,062.5289	$1,062.53	$1,062.55	$1,062.50