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	$152.96	6.494%	$162.8932	$162.89	$162.90	$162.90
Purchase #2	$167.57	10.152%	$184.5817	$184.58	$184.60	$184.60
Purchase #3	$111.48	8.428%	$120.8755	$120.88	$120.90	$120.90
Purchase #4	$187.63	5.299%	$197.5725	$197.57	$197.55	$197.60
Purchase #5	$75.58	8.500%	$82.0043	$82.00	$82.00	$82.00
Purchase #6	$84.31	6.281%	$89.6055	$89.61	$89.60	$89.60
Purchase #7	$154.47	13.213%	$174.8801	$174.88	$174.90	$174.90
7 purchase totals =	$934.00		$1,012.4128	$1,012.41	$1,012.45	$1,012.50