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	$59.54	3.404%	$61.5667	$61.57	$61.55	$61.60
Purchase #2	$11.41	8.846%	$12.4193	$12.42	$12.40	$12.40
Purchase #3	$50.89	3.281%	$52.5597	$52.56	$52.55	$52.60
Purchase #4	$32.34	3.304%	$33.4085	$33.41	$33.40	$33.40
Purchase #5	$213.99	9.488%	$234.2934	$234.29	$234.30	$234.30
Purchase #6	$54.47	10.621%	$60.2553	$60.26	$60.25	$60.30
Purchase #7	$46.47	12.434%	$52.2481	$52.25	$52.25	$52.20
7 purchase totals =	$469.11		$506.7510	$506.76	$506.70	$506.80