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	$194.55	5.331%	$204.9215	$204.92	$204.90	$204.90
Purchase #2	$146.60	10.519%	$162.0209	$162.02	$162.00	$162.00
Purchase #3	$221.54	9.476%	$242.5331	$242.53	$242.55	$242.50
Purchase #4	$30.94	13.240%	$35.0365	$35.04	$35.05	$35.00
Purchase #5	$123.38	13.704%	$140.288	$140.29	$140.30	$140.30
Purchase #6	$135.48	11.801%	$151.468	$151.47	$151.45	$151.50
Purchase #7	$143.63	10.554%	$158.7887	$158.79	$158.80	$158.80
7 purchase totals =	$996.12		$1,095.0567	$1,095.06	$1,095.05	$1,095.00