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	$123.74	5.684%	$130.7734	$130.77	$130.75	$130.80
Purchase #2	$83.78	6.814%	$89.4888	$89.49	$89.50	$89.50
Purchase #3	$41.55	10.719%	$46.0037	$46.00	$46.00	$46.00
Purchase #4	$33.43	9.497%	$36.6048	$36.60	$36.60	$36.60
Purchase #5	$225.72	6.376%	$240.1119	$240.11	$240.10	$240.10
Purchase #6	$142.69	6.389%	$151.8065	$151.81	$151.80	$151.80
Purchase #7	$42.67	9.106%	$46.5555	$46.56	$46.55	$46.60
7 purchase totals =	$693.58		$741.3446	$741.34	$741.30	$741.40