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	$195.58	8.360%	$211.9305	$211.93	$211.95	$211.90
Purchase #2	$126.46	5.751%	$133.7327	$133.73	$133.75	$133.70
Purchase #3	$183.64	9.339%	$200.7901	$200.79	$200.80	$200.80
Purchase #4	$98.68	11.494%	$110.0223	$110.02	$110.00	$110.00
Purchase #5	$74.87	10.311%	$82.5898	$82.59	$82.60	$82.60
Purchase #6	$170.78	8.754%	$185.7301	$185.73	$185.75	$185.70
Purchase #7	$83.84	13.511%	$95.1676	$95.17	$95.15	$95.20
7 purchase totals =	$933.85		$1,019.9631	$1,019.96	$1,020.00	$1,019.90