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	$107.52	10.356%	$118.6548	$118.65	$118.65	$118.70
Purchase #2	$134.48	10.272%	$148.2938	$148.29	$148.30	$148.30
Purchase #3	$135.57	10.840%	$150.2658	$150.27	$150.25	$150.30
Purchase #4	$55.49	6.765%	$59.2439	$59.24	$59.25	$59.20
Purchase #5	$145.53	7.237%	$156.062	$156.06	$156.05	$156.10
Purchase #6	$166.89	11.272%	$185.7018	$185.70	$185.70	$185.70
Purchase #7	$227.50	6.538%	$242.374	$242.37	$242.35	$242.40
7 purchase totals =	$972.98		$1,060.5961	$1,060.58	$1,060.55	$1,060.70