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	$191.64	4.778%	$200.7966	$200.80	$200.80	$200.80
Purchase #2	$225.74	7.356%	$242.3454	$242.35	$242.35	$242.30
Purchase #3	$52.31	8.530%	$56.772	$56.77	$56.75	$56.80
Purchase #4	$135.97	13.432%	$154.2335	$154.23	$154.25	$154.20
Purchase #5	$37.78	7.757%	$40.7106	$40.71	$40.70	$40.70
Purchase #6	$212.78	4.816%	$223.0275	$223.03	$223.05	$223.00
Purchase #7	$127.50	3.374%	$131.8019	$131.80	$131.80	$131.80
7 purchase totals =	$983.72		$1,049.6875	$1,049.69	$1,049.70	$1,049.60