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	$182.93	5.359%	$192.7332	$192.73	$192.75	$192.70
Purchase #2	$91.54	8.629%	$99.439	$99.44	$99.45	$99.40
Purchase #3	$186.52	11.597%	$208.1507	$208.15	$208.15	$208.20
Purchase #4	$115.76	13.822%	$131.7603	$131.76	$131.75	$131.80
Purchase #5	$172.85	4.305%	$180.2912	$180.29	$180.30	$180.30
Purchase #6	$112.41	13.599%	$127.6966	$127.70	$127.70	$127.70
Purchase #7	$154.63	10.514%	$170.8878	$170.89	$170.90	$170.90
7 purchase totals =	$1,016.64		$1,110.9588	$1,110.96	$1,111.00	$1,111.00