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	$162.62	11.234%	$180.8887	$180.89	$180.90	$180.90
Purchase #2	$71.38	8.268%	$77.2817	$77.28	$77.30	$77.30
Purchase #3	$77.27	7.392%	$82.9818	$82.98	$83.00	$83.00
Purchase #4	$243.63	10.783%	$269.9006	$269.90	$269.90	$269.90
Purchase #5	$196.88	7.270%	$211.1932	$211.19	$211.20	$211.20
Purchase #6	$125.51	11.130%	$139.4793	$139.48	$139.50	$139.50
Purchase #7	$59.25	3.390%	$61.2586	$61.26	$61.25	$61.30
7 purchase totals =	$936.54		$1,022.9839	$1,022.98	$1,023.05	$1,023.10