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	$65.43	8.572%	$71.0387	$71.04	$71.05	$71.00
Purchase #2	$169.92	4.424%	$177.4373	$177.44	$177.45	$177.40
Purchase #3	$190.29	12.516%	$214.1067	$214.11	$214.10	$214.10
Purchase #4	$200.31	4.398%	$209.1196	$209.12	$209.10	$209.10
Purchase #5	$48.96	8.159%	$52.9546	$52.95	$52.95	$53.00
Purchase #6	$113.31	9.362%	$123.9181	$123.92	$123.90	$123.90
Purchase #7	$165.56	3.309%	$171.0384	$171.04	$171.05	$171.00
7 purchase totals =	$953.78		$1,019.6134	$1,019.62	$1,019.60	$1,019.50