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	$174.93	7.551%	$188.139	$188.14	$188.15	$188.10
Purchase #2	$192.80	6.209%	$204.771	$204.77	$204.75	$204.80
Purchase #3	$167.26	10.819%	$185.3559	$185.36	$185.35	$185.40
Purchase #4	$69.94	4.188%	$72.8691	$72.87	$72.85	$72.90
Purchase #5	$160.84	13.203%	$182.0757	$182.08	$182.10	$182.10
Purchase #6	$65.53	8.515%	$71.1099	$71.11	$71.10	$71.10
Purchase #7	$217.50	13.785%	$247.4824	$247.48	$247.50	$247.50
7 purchase totals =	$1,048.80		$1,151.8030	$1,151.81	$1,151.80	$1,151.90