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	$154.65	8.141%	$167.2401	$167.24	$167.25	$167.20
Purchase #2	$91.76	9.730%	$100.6882	$100.69	$100.70	$100.70
Purchase #3	$127.27	11.268%	$141.6108	$141.61	$141.60	$141.60
Purchase #4	$131.46	9.717%	$144.234	$144.23	$144.25	$144.20
Purchase #5	$172.62	13.258%	$195.506	$195.51	$195.50	$195.50
Purchase #6	$159.91	13.837%	$182.0367	$182.04	$182.05	$182.00
Purchase #7	$87.60	4.734%	$91.747	$91.75	$91.75	$91.70
7 purchase totals =	$925.27		$1,023.0628	$1,023.07	$1,023.10	$1,022.90