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	$148.89	5.490%	$157.0641	$157.06	$157.05	$157.10
Purchase #2	$165.92	13.114%	$187.6787	$187.68	$187.70	$187.70
Purchase #3	$221.43	12.137%	$248.305	$248.31	$248.30	$248.30
Purchase #4	$36.30	3.631%	$37.6181	$37.62	$37.60	$37.60
Purchase #5	$246.34	12.636%	$277.4675	$277.47	$277.45	$277.50
Purchase #6	$53.85	9.393%	$58.9081	$58.91	$58.90	$58.90
Purchase #7	$89.77	11.279%	$99.8952	$99.90	$99.90	$99.90
7 purchase totals =	$962.50		$1,066.9367	$1,066.95	$1,066.90	$1,067.00