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	$180.60	7.206%	$193.614	$193.61	$193.60	$193.60
Purchase #2	$169.78	12.570%	$191.1213	$191.12	$191.10	$191.10
Purchase #3	$99.65	11.544%	$111.1536	$111.15	$111.15	$111.20
Purchase #4	$238.75	10.191%	$263.081	$263.08	$263.10	$263.10
Purchase #5	$230.41	4.582%	$240.9674	$240.97	$240.95	$241.00
Purchase #6	$85.43	3.150%	$88.121	$88.12	$88.10	$88.10
Purchase #7	$154.49	7.387%	$165.9022	$165.90	$165.90	$165.90
7 purchase totals =	$1,159.11		$1,253.9605	$1,253.95	$1,253.90	$1,254.00