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	$184.72	12.283%	$207.4092	$207.41	$207.40	$207.40
Purchase #2	$83.89	9.306%	$91.6968	$91.70	$91.70	$91.70
Purchase #3	$145.84	4.453%	$152.3343	$152.33	$152.35	$152.30
Purchase #4	$212.96	9.422%	$233.0251	$233.03	$233.05	$233.00
Purchase #5	$28.69	4.573%	$30.002	$30.00	$30.00	$30.00
Purchase #6	$125.55	6.667%	$133.9204	$133.92	$133.90	$133.90
Purchase #7	$149.89	12.229%	$168.22	$168.22	$168.20	$168.20
7 purchase totals =	$931.54		$1,016.6078	$1,016.61	$1,016.60	$1,016.50