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	$206.36	3.761%	$214.1212	$214.12	$214.10	$214.10
Purchase #2	$37.34	12.150%	$41.8768	$41.88	$41.90	$41.90
Purchase #3	$221.90	7.842%	$239.3014	$239.30	$239.30	$239.30
Purchase #4	$171.38	11.600%	$191.2601	$191.26	$191.25	$191.30
Purchase #5	$56.74	9.243%	$61.9845	$61.98	$62.00	$62.00
Purchase #6	$67.83	6.677%	$72.359	$72.36	$72.35	$72.40
Purchase #7	$185.26	3.408%	$191.5737	$191.57	$191.55	$191.60
7 purchase totals =	$946.81		$1,012.4767	$1,012.47	$1,012.45	$1,012.60